feat: support multiple flakes

[fym998]

Description

Similar to #109 , but simpler. Use nix flake update --flake <dir> to handle flakes. Tested here: fym998/update-flake-lock-test-template/pull/1.

Checklist

• Tested functionality against a test repository (see "How to test changes")
• Added or updated relevant documentation (leave unchecked if not applicable)

[fym998]

@cole-h make a review please 🙏

[HeitorAugustoLN]

I've been using this PR version of the action for a while, and the only thing that bothers me is that I am not able to set different commit messages for each flake. Can you add this functionality?

[fym998]

I've been using this PR version of the action for a while, and the only thing that bothers me is that I am not able to set different commit messages for each flake. Can you add this functionality?

Thanks for feedback! See fym998/update-flake-lock@commit-summary-per-flake

Example:

      - uses: fym998/update-flake-lock@commit-summary-per-flake
        with:
          flakes: |
            .
            sub-flake/
            sub-flake-empty-commit-summary/
            sub-flake-null-commit-summary/
            sub-flake-not-listed/
          commit-msg: default commit summary message
          commit-msg-per-flake: |
            {
              ".": "Update flake.lock for main flake",
              "sub-flake/": "Update flake.lock for sub-flake",
              "sub-flake-empty-commit-summary/": "",
              "sub-flake-null-commit-summary/": null
            }

[HeitorAugustoLN]

Cool, why not just use something like:

      - uses: fym998/update-flake-lock@commit-summary-per-flake
        with:
          flakes: |
            .
            sub-flake/
            sub-flake-empty-commit-summary/
            sub-flake-null-commit-summary/
            sub-flake-not-listed/
          commit-msg: |
            Update flake.lock for main flake
            Update flake.lock for sub-flake
            ''

instead? I think its a better ux