Attempt to prevent accidental merges to `stable` due to GitHub's default behaviour of opening PRs against it.
I've intentionally opened this PR against `stable` to test the functionality ;)
## Issue Addressed
N/A
## Proposed Changes
Remove the MacOs tests. They routinely fail, causing bors to retry and slowing down the whole merge process.
## Additional Info
N/A
Co-authored-by: Michael Sproul <michael@sigmaprime.io>