support standard yaml syntax for files field

[nicola-lunghi]

Currently the files to be uploaded are specified with a comma separated list of names.
Having a syntax like the upload-artifact action would be really nice:

https://github.com/actions/upload-artifact?tab=readme-ov-file#upload-using-multiple-paths-and-exclusions

    - uses: ncipollo/release-action@v1
      with:
        artifacts: |
          path/output/bin/
          path/output/test-results
          !path/**/*.tmp

[ncipollo]

You can use similar grep rules here, the paths are just delimited by a comma rather than a new line. At some point I may implement #322 which would give you the option of specifying the delimiter you want.