chore: prepare 0.6.1rc4

[utensil]

Trying to make zenodo release work after updating webbook access token.

Bump from 0.6.1rc3 to 0.6.1rc4.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.90%. Comparing base (1de3b65) to head (32a5626).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #602   +/-   ##
=======================================
  Coverage   73.90%   73.90%           
=======================================
  Files          23       23           
  Lines        4518     4518           
=======================================
  Hits         3339     3339           
  Misses       1179     1179           

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[utensil]

The zenodo release of galgebra seems to be broken since last year:

I have tried unlink/link github account and update the webhook token, but it seems to be still:

{
    "error_id": "b93ddb726dce49ababe969133a1611e0",
    "errors": "401 Bad credentials"
}

from zenodo side. From the github side, inspecting deliver log https://github.com/pygae/galgebra/settings/hooks/213441553?tab=deliveries also didn't get me anywhere.

There is a secret there but I didn't change it.

@hugohadfield @eric-wieser @arsenovic do you still recall how this was set up? Thanks!