Right now releaser-pleaser pushes the branch even if it is only for a "rebase",
this wastes CI resources. Instead, it should only push when there are changes
to the files it owns.
- **Old**: Push when there is a diff origin/release-pr..release-pr
- **New**: Push when the these two diffs are not the same:
origin/main..release-pr
$(git merge-base origin/main origin/release-pr)..release-pr
Closes#92
