Get changed files based on merge base when checking `pull_request` actions trigger (#34106)#34120

lunny merged 1 commit intogo-gitea:release/v1.23go-gitea/gitea:release/v1.23from

Zettat123:backport-34106-v1.23Zettat123/gitea:backport-34106-v1.23Copy head branch name to clipboard