chore(ci): replace hardcoded GAR path with GCP_REGISTRY variable

Author: Genesis Alvarez

.github/workflows/production.yaml

@@ -15,7 +15,7 @@ on:
 
 env:
   REQUIRED_MODULES: session_redis,logging_json,attachment_s3,cloud_platform_exoscale # list of addional addons to install separated by comma
-  GAR_BASE: us-docker.pkg.dev/${{ secrets.GKE_PROJECT }}/odoo-gob
+  GAR_BASE: ${{ vars.GCP_REGISTRY}}
   HUB_BASE: gobdo/odoo-gob
   IMAGE_LOCATION: iterativodo/dockerdoo
   ENV: "prod"