Add version bump github action

[zkurtz]

uv recently added the uv version --bump command. I'm proposing to wrap this in a convenient GitHub Action, similar to how phips28/gh-action-bump-version works for npm projects.

Scope: Version management operations like:

• Check if version needs bumping
• Bump version (default to patch; minor+ would require harder logic)
• Commit and push changes
• Optional git tagging

Would you encourage the community creating this, or prefer it stays as manual uv version commands in workflows?

[zkurtz]

apologies, meant to post under the main uv issues page, as this is pretty clearly out of scope for "setup"