copy-to-branches

Copies files from any 'key' branch to all other branches. By default, LICENSE, NOTICE and README.md will be copied from the main/master branch to all branches, but it can be configured so you can specify a list of branches, a list of files or branches to exclude from all branches. Maintained by planetoftheweb on GitHub, where it has earned 18 stars from the community.

It's actively developed around actions, alpine, bash, and is a solid reference for anyone building with these tools.