Invalid YAML in test_cpu suite rejected by yaml-cpp 0.9.0

[OPNA2608]

NixOS/nixpkgs#560590 (comment)

When built against yaml-cpp version 0.9.0, test_cpu_exec fails:

[ 129/1169] [Config / inactive_color_space_precedence                    ] - PASSED
/build/source/tests/cpu/Config_tests.cpp:6502:
FAILED: exception thrown from config = OCIO::Config::CreateFromStream(is): "Error: Loading the OCIO profile failed. yaml-cpp: error at line 25, column 1: plain value cannot start with flow indicator character"
Segmentation fault         (core dumped) ./test_cpu_exec

OpenColorIO/tests/cpu/Config_tests.cpp

Lines 6492 to 6502 in c52966a

	std::string configStr;
	configStr += InactiveCSConfigStart;
	// Test a multi-line list.
	configStr += "inactive_colorspaces: [cs1\t\n \n, \ncs2]\n";
	configStr += InactiveCSConfigEnd;
	std::istringstream is;
	is.str(configStr);
	OCIO::ConstConfigRcPtr config;
	OCIO_CHECK_NO_THROW(config = OCIO::Config::CreateFromStream(is));

If you want to continue using funky YAML in this test, then the continued lines of the array with more than just whitespace content must be indented. Example fix (without CLA signature): #2339