add auth step to CI

Author: Mladen Rusev

.github/workflows/tests.yaml

@@ -87,6 +87,9 @@ jobs:
         with:
           project_id: machineidentitysecurity-jsci-e
 
+      - name: Configure Docker for Google Artifact Registry
+        run: gcloud auth configure-docker europe-west1-docker.pkg.dev
+
       - name: Install dependencies
         run: |
           gcloud components install gke-gcloud-auth-plugin