restore credentials to coverage workflow

Author: jnu

.github/workflows/pycov.yaml

@@ -18,9 +18,9 @@ jobs:
       - uses: actions/checkout@v3
 
       - name: Setup gcloud Auth
-        uses: google-github-actions/auth@v1
+        uses: google-github-actions/auth@v3
         with:
-          credentials_json: "${{ secrets.GC_SERVICE_KEY }}"
+          credentials_json: "${{ secrets.GCLOUD_CREDENTIALS_JSON }}"
 
       - name: Setup gcloud CLI
         uses: google-github-actions/setup-gcloud@main