Merging PR branch and deleting before actions finish running cause actions to fail

[arunsathiya]

• https://github.com/arunsathiya/leetcode/actions/runs/7325516140
• https://github.com/arunsathiya/leetcode/actions/runs/7325430223

Clearly the correct behavior at the moment because, the branch just doesn't exist due to me merging immediately with gh pr merge <number> -md command. Need to think of a way to handle this without appearing as a failure in actions.

[arunsathiya]

Something like skip the workflow if the branch is missing? Or more specifically, if a new job is already running for main along with the diff in the PR, skip the PR job.

[arunsathiya]

cancel-in-progress could potentially help:

https://github.com/supabase/supabase/blob/f38cc4b946776f4f029e3b049b6ed497076efe76/.github/workflows/studio-tests.yml#L18-L21