Scheduled workflows fixes

[MikeMcQuaid]

• 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.

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• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew tests with your changes locally?

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[dawidd6]

Force push does not seem to work:
https://github.com/Homebrew/brew/pull/8468/checks?check_run_id=1021283749

[MikeMcQuaid]

@dawidd6 this should fix it: Homebrew/actions#64