Scheduled workflows fixes

- Ensure `spdx.yml` has same fixes as `tapioca.yml`.
- Don't `reset --hard` to ensure that `brew` commands used are those in
  the same branch rather than always from `origin/master`
- Don't check for an existing branch but instead force-push to it if
  there's any updates.
- Provide sample `brew typecheck` command that can be used.