chore(renovate): update GitHub Actions major versions in docs (#7584)
## Summary
Originally wanted to update the reference to `astral-sh/setup-uv` in
https://docs.astral.sh/uv/guides/integration/github/, but thought it
could be nice to automate those updates through Renovate. The custom
manager will look for any major version GitHub Action reference in any
Markdown file in `docs` directory, and raise a PR to update it.
Possible improvements:
- We could separate those updates from updating the actions updates for
uv's own GitHub Actions workflow, which would end up raising 2 different
PRs instead of grouping them (example of the current behaviour without
this improvement in
https://github.com/mkniewallner/mkv-playground/pull/4 where we update
the doc reference at the same time as a real dependency usage in a
workflow).
- ~Should the PRs be raised immediately, to handle the update as soon as
possible, instead of waiting for the regular weekly Monday schedule?
This would ensure that `astral-sh/setup-uv` references are handled as
early as possible.~ done in
https://github.com/astral-sh/uv/pull/7584/commits/6af7f4575071091b337a9fd3f24bc4459923f2a2
## Test Plan
I've tested that with
https://github.com/mkniewallner/mkv-playground/blob/00ddfb69003843ad57d05f9ef036e655aaf765d7/renovate.json5
and
https://github.com/mkniewallner/mkv-playground/blob/00ddfb69003843ad57d05f9ef036e655aaf765d7/docs/integeration/foo.md,
where Renovate raised 2 PRs:
- https://github.com/mkniewallner/mkv-playground/pull/13
- https://github.com/mkniewallner/mkv-playground/pull/4
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Co-authored-by: Zanie Blue <contact@zanie.dev>