* ci: stop building `push` on all branches
* ci: stop co-authoring on generated commits
The current commit message is quite verbose and
co-authors the original author.
In @nekowinston's words:
"there's no reason i'm co-authored when i merge
a PR in that changes a single line in the readme
:baldkek:"
This commit reduces the verbosity of the commit
message and doesn't co-author the merger.