Trac role to GitHub

[roed314]

📚 Description

Changes the :trac: role to point to github instead, and changes deprecation and stopgap warnings. Changes all the resulting urls that are printed in doctests, as well as various comments in code.

Does not update the developer documentation to explain how to use github.

[kwankyu]

How about introducing a new role :gh: to replace the role of :trac: at this time? Or later in a new PR?

We may keep both for some time.

[tobiasdiez]

Maybe a general purpose issue role, so that we don't have to change everything in a few years when we migrate to the next hip and happening platform?

[kwankyu]

Never in a few years :-)

Like :trac:, I think that specificity of :gh: would explain the role more than a general purpose name. And it's short!

[codecov-commenter]

Codecov Report

Base: 88.59% // Head: 88.58% // Decreases project coverage by -0.02% ⚠️

Coverage data is based on head (12493ab) compared to base (fbb4127).
Patch coverage: 97.05% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #35015      +/-   ##
===========================================
- Coverage    88.59%   88.58%   -0.02%     
===========================================
  Files         2140     2140              
  Lines       396961   396958       -3     
===========================================
- Hits        351677   351634      -43     
- Misses       45284    45324      +40     

Impacted Files	Coverage Δ
src/sage/algebras/free_algebra_element.py	82.50% <ø> (ø)
src/sage/algebras/fusion_rings/fusion_ring.py	93.93% <ø> (ø)
src/sage/algebras/lie_algebras/free_lie_algebra.py	95.43% <ø> (ø)
src/sage/algebras/lie_algebras/lie_algebra.py	91.10% <ø> (ø)
src/sage/algebras/lie_algebras/morphism.py	90.07% <ø> (ø)
src/sage/algebras/quatalg/quaternion_algebra.py	92.68% <ø> (ø)
src/sage/categories/category_with_axiom.py	98.71% <ø> (ø)
...age/categories/finite_complex_reflection_groups.py	79.12% <ø> (ø)
src/sage/categories/homset.py	92.66% <ø> (ø)
src/sage/categories/magmas.py	97.63% <ø> (ø)
... and 155 more

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[roed314]

Sorry about that; I had meant to just avoid the doc directory in this PR, but accidentally ran sed one level too high in the source tree. I think the relevant files should be reverted now.

[mkoeppe]

Looking good.

[dimpase]

there is still a number of explicit (rewritten to URLs) trac.sagemath.org/ticket/<...> links in docstrings which should become :trac:<...>.
(in another PR)

[github-actions]

Documentation preview for this PR is ready! 🎉
Built with commit: 12493ab

[dimpase]

@vbraun - can you merge this soon? It's touching a lo of files for a good reason, and having it linger on
is entering a rebase hell...

[mkoeppe]

I think the best way to request this is to mark with a high-priority label