Add colour to GitHub Actions output

[hugovk]

Following the merge of #127223, #127719, #127877, #128498 and #128687, we can now enable colour in the unittest and test.regrtest output on GitHub Actions using FORCE_COLOR.

The biggest benefit is it helps us find failures when scrolling the long logs, and usually the reason to open the logs in the first place is to find a failure.

For example, here's a forced failure in another branch:

https://github.com/hugovk/cpython/actions/runs/12915439756/job/36017613160

Accessibility check: it's important not to rely on colour alone to confer information, and the current textual output is not changed, and continues to say pass/skip/fail as now. The colour is an addition.

[brandtbucher]

JIT CI changes look good!

[hugovk]

Thank you flaky test, it was easy to find you and conclude not relevant here, and restart the job :)

https://github.com/python/cpython/actions/runs/12916819582/job/36021859818?pr=129196

[hugovk]

unittest and test.regrtest don't have colour in 3.13 or earlier, but let's backport these to keep the diffs between the files smaller for future backports, and it can enable colour in any other tools on the CI that support it.

[miss-islington-app]

Thanks @hugovk for the PR 🌮🎉.. I'm working now to backport this PR to: 3.12, 3.13.
🐍🍒⛏🤖

[bedevere-app]

GH-129198 is a backport of this pull request to the 3.13 branch.

[miss-islington-app]

Sorry, @hugovk, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 298dda57709c45cbcb44831e0d682dc071af5293 3.12

[bedevere-app]

GH-129199 is a backport of this pull request to the 3.12 branch.