run promote on pull request

Author: zglicz

.github/workflows/build.yml

@@ -31,7 +31,7 @@ jobs:
   promote:
     needs: build
     if: >
-      github.event_name == 'push'
+      github.event_name == 'push' || github.event_name == 'pull_request'
     runs-on: github-ubuntu-latest-s
     permissions:
       id-token: write