build: workaround until GCP fixes dependency issue in spanner lib

This commit works around a strict dependency issue caused by the
`@google-cloud/spanner` library. See:

GoogleCloudPlatform/grpc-gcp-node#187.

Author: devversion

Diff for: package.json

@@ -167,6 +167,11 @@
           "clonedeep": "*"
         }
       },
+      "grpc-gcp": {
+        "dependencies": {
+          "protobufjs": "7.4.0"
+        }
+      },
       "@angular-eslint/[email protected]": {
         "peerDependencies": {
           "@typescript-eslint/parser": "*",