danger: Update PR prefix pattern (#29432)

This PR updates the Danger PR prefix pattern to allow underscores (`_`)
and spaces (` `) in the prefix.

Release Notes:

- N/A
5f9c91d05aMarshall Bowers committed on 4/25/2025, 5:19:56 PM· committed by GitHubparent6692bd9
1 file changedLine totals unavailable