Add registry.redhat.io login to GH workflow

The bundle generation step resolves image tags to digests, which
requires pulling from registry.redhat.io (for the PostgreSQL image).
Add authentication so the CI runner can access the Red Hat registry.

Author: lpiwowar

.github/workflows/build-and-push.yaml

@@ -68,6 +68,13 @@ jobs:
           username: ${{ secrets.QUAY_USERNAME }}
           password: ${{ secrets.QUAY_PASSWORD }}
 
+      - name: Log in to Red Hat Registry
+        uses: docker/login-action@v4
+        with:
+          registry: registry.redhat.io
+          username: ${{ secrets.REDHAT_REGISTRY_USERNAME }}
+          password: ${{ secrets.REDHAT_REGISTRY_PASSWORD }}
+
       - name: Build operator image
         run: |
           make docker-build IMG=$OPERATOR_IMAGE