Cleanup and pin MystBin dependencies

[AbstractUmbra]

Description

This PR cleans up the Python dependencies and also pins them to versions. Currently this is exact pinning which will help cache the build artifacts correctly.

I removed the pyyaml dependency as it was not used in the codebase, and I also removed the humanize dependency as it was used in a single place, with which I replaced with a handwritten util.

Checklist

• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
  • I have updated the changelog with a quick recap of my changes.
• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed)
• This PR is not a code change (e.g. documentation, README, ...)
• I have read and agree to the Developer Certificate of Origin for this contribution