Add OSDU_GCP_VENDOR

.gitlab-ci.yml

 variables:
   OSDU_GCP_APPLICATION_NAME: os-notification
+  OSDU_GCP_VENDOR: gcp
   OSDU_GCP_SERVICE: notification
   OSDU_GCP_ENV_VARS: APP_PROJECT=${OSDU_GCP_PROJECT},APP_ENTITLEMENTS=${OSDU_GCP_ENTITLEMENTS_URL},APP_REGISTER=${OSDU_GCP_REGISTER_URL},APP_GOOGLEAUDIENCE=${GOOGLE_AUDIENCE}