Prevent README.md updates from triggering an alpha dev release on Modrinth (Github Actions)

[szymon-off]

Improve the Github Actions devbuild workflow to ignore updates only containing changes for the README.md.

Possible ways of achieving this:

• Detect a commit property(name, tag?) to prevent workflow from triggering (would require maintainers to include such property in all README update commits).
• Or just check in which files the changes from a specific commit are located.