ci: Don't log in to container registry for forked PRs

Signed-off-by: Christian Kadner <[email protected]>

Author: ckadner

.github/workflows/build.yml

@@ -51,13 +51,15 @@ jobs:
 
       - name: "Log in to container registry (server-release)"
         uses: docker/login-action@v3
+        if: github.event_name != 'pull_request'
         with:
           registry: ${{ env.IMAGE_REGISTRY }}
           username: ${{ secrets.WXPE_QUAY_USER }}
           password: ${{ secrets.WXPE_QUAY_TOKEN }}
 
       - name: "Log in to container registry (cache image)"
         uses: docker/login-action@v3
+        if: github.event_name != 'pull_request'
         with:
           registry: ${{ env.CACHE_REGISTRY }}
           username: ${{ github.actor }}