fix: release PHP 8-compatible version

[ousamabenyounes]

Promote the PHP 8-compatible 2.0.0 beta version identifier to stable 2.0.0. Add a PHPT regression test covering the extension-reported version.

Test verification (RED → GREEN)

With the fix reverted, the new test fails (RED):

More .INIs  : /usr/local/etc/php/conf.d/docker-php-ext-sodium.ini 
---------------------------------------------------------------------
PHP         : /usr/local/bin/php-cgi 
PHP_SAPI    : cgi-fcgi
PHP_VERSION : 8.1.31
ZEND_VERSION: 4.1.31
PHP_OS      : Linux - Linux 4e76685ad42d 7.0.0-22-generic #22-Ubuntu SMP PREEMPT_DYNAMIC Mon May 25 15:54:34 UTC 2026 x86_64
INI actual  : /work/extension
More .INIs  : /usr/local/etc/php/conf.d/docker-php-ext-sodium.ini
--------------------------------------------------------------------- 
---------------------------------------------------------------------
PHP         : /usr/local/bin/phpdbg 
PHP_SAPI    : phpdbg
PHP_VERSION : 8.1.31
ZEND_VERSION: 4.1.31
PHP_OS      : Linux - Linux 4e76685ad42d 7.0.0-22-generic #22-Ubuntu SMP PREEMPT_DYNAMIC Mon May 25 15:54:34 UTC 2026 x86_64
INI actual  : /work/extension
More .INIs  : /usr/local/etc/php/conf.d/docker-php-ext-sodium.ini
---------------------------------------------------------------------
CWD         : /work/extension
Extra dirs  : 
VALGRIND    : Not used
=====================================================================
Running selected tests.
TEST 1/1 [tests/version.phpt]
�[1;31mFAIL�[0m Check stable PHP 8-compatible version [tests/version.phpt] 
=====================================================================
Number of tests :    1                 1
Tests skipped   :    0 (  0.0%) --------
Tests warned    :    0 (  0.0%) (  0.0%)
Tests failed    :    1 (100.0%) (100.0%)
Tests passed    :    0 (  0.0%) (  0.0%)
---------------------------------------------------------------------
Time taken      :    0 seconds
=====================================================================

=====================================================================
FAILED TEST SUMMARY
---------------------------------------------------------------------
Check stable PHP 8-compatible version [tests/version.phpt]
=====================================================================

With the fix applied, the test passes (GREEN):

PHP         : /usr/local/bin/php 
PHP_SAPI    : cli
PHP_VERSION : 8.1.31
ZEND_VERSION: 4.1.31
PHP_OS      : Linux - Linux eba7caab3d29 7.0.0-22-generic #22-Ubuntu SMP PREEMPT_DYNAMIC Mon May 25 15:54:34 UTC 2026 x86_64
INI actual  : /work/extension
More .INIs  : /usr/local/etc/php/conf.d/docker-php-ext-sodium.ini 
---------------------------------------------------------------------
PHP         : /usr/local/bin/php-cgi 
PHP_SAPI    : cgi-fcgi
PHP_VERSION : 8.1.31
ZEND_VERSION: 4.1.31
PHP_OS      : Linux - Linux eba7caab3d29 7.0.0-22-generic #22-Ubuntu SMP PREEMPT_DYNAMIC Mon May 25 15:54:34 UTC 2026 x86_64
INI actual  : /work/extension
More .INIs  : /usr/local/etc/php/conf.d/docker-php-ext-sodium.ini
--------------------------------------------------------------------- 
---------------------------------------------------------------------
PHP         : /usr/local/bin/phpdbg 
PHP_SAPI    : phpdbg
PHP_VERSION : 8.1.31
ZEND_VERSION: 4.1.31
PHP_OS      : Linux - Linux eba7caab3d29 7.0.0-22-generic #22-Ubuntu SMP PREEMPT_DYNAMIC Mon May 25 15:54:34 UTC 2026 x86_64
INI actual  : /work/extension
More .INIs  : /usr/local/etc/php/conf.d/docker-php-ext-sodium.ini
---------------------------------------------------------------------
CWD         : /work/extension
Extra dirs  : 
VALGRIND    : Not used
=====================================================================
Running selected tests.
TEST 1/1 [tests/version.phpt]
�[1;32mPASS�[0m Check stable PHP 8-compatible version [tests/version.phpt] 
=====================================================================
Number of tests :    1                 1
Tests skipped   :    0 (  0.0%) --------
Tests warned    :    0 (  0.0%) (  0.0%)
Tests failed    :    0 (  0.0%) (  0.0%)
Tests passed    :    1 (100.0%) (100.0%)
---------------------------------------------------------------------
Time taken      :    0 seconds
=====================================================================

Full local suite

Command: docker run --rm -v "$PWD":/work -w /work/extension php:8.1.31-cli-bookworm bash -lc 'set -e; apt-get update -qq; apt-get install -y -qq autoconf g++ make pkg-config >/dev/null; phpize >/dev/null; ./configure --enable-meminfo >/dev/null; make -j2 >/dev/null; REPORT_EXIT_STATUS=1 NO_INTERACTION=1 make test' && docker run --rm -v "$PWD/analyzer":/app -w /app --entrypoint sh composer:2.8.11 -lc 'set -e; composer config --global platform.php 8.1.31; composer install --no-interaction --prefer-dist' && docker run --rm -v "$PWD/analyzer":/app -w /app php:8.1.31-cli-bookworm php vendor/bin/phpspec run

  - Installing symfony/polyfill-ctype (v1.37.0): Extracting archive
  - Installing symfony/deprecation-contracts (v3.7.1): Extracting archive
  - Installing symfony/yaml (v6.4.45): Extracting archive
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  - Installing symfony/polyfill-mbstring (v1.38.2): Extracting archive
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  - Installing symfony/service-contracts (v3.7.3): Extracting archive
  - Installing symfony/polyfill-php80 (v1.37.0): Extracting archive
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  - Installing symfony/console (v5.4.47): Extracting archive
  - Installing sebastian/recursion-context (5.0.2): Extracting archive
  - Installing sebastian/exporter (5.1.4): Extracting archive
  - Installing sebastian/diff (5.1.1): Extracting archive
  - Installing sebastian/comparator (5.0.5): Extracting archive
  - Installing webmozart/assert (1.12.1): Extracting archive
  - Installing phpdocumentor/reflection-docblock (5.6.7): Extracting archive
  - Installing doctrine/instantiator (2.0.0): Extracting archive
  - Installing phpspec/prophecy (v1.22.0): Extracting archive
  - Installing phpspec/php-diff (v1.1.3): Extracting archive
  - Installing phpspec/phpspec (7.6.0): Extracting archive
  - Installing symfony/filesystem (v5.4.45): Extracting archive
  - Installing symfony/serializer (v5.4.45): Extracting archive
  0/35 [>---------------------------]   0%
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/  skipped: 0%  /  pending: 0%  / passed: 100%  /  failed: 0%   /  broken: 0%   /  1 examples����������6 examples
2 specs
6 examples (6 passed)
11ms

Fix #125