ci: Fix target branch for Zippy version bumps (#54346)

I assumed the action would pick up the branch from the context - turns
out it did not.

Release Notes:

- N/A
261c07358eFinn Evers committed on 4/20/2026, 6:25:44 PM· committed by GitHubparent57e01b3
2 files changedLine totals unavailable