Don't push on pull request

Author: mike-potter

.github/workflows/default.yml

@@ -87,5 +87,5 @@ jobs:
           file: ./src/Dockerfile
           build-args: CLI_VERSION=php${{ matrix.version }}
           platforms: linux/amd64,linux/arm64
-          push: true
+          push:  ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.prep.outputs.tags }}