fix accesss to database on ci

.gitlab-ci.yml

@@ -20,6 +20,8 @@ variables:
     # Configure postgres environment variables (https://hub.docker.com/r/_/postgres/)
     POSTGRES_USER: postgres
     POSTGRES_PASSWORD: postgres
+    # configure database access
+    DATABASE_URL: postgresql://postgres:postgres@db:5432/postgres?serverVersion=12&charset=utf8
     # fetch the chill-app using git submodules
     GIT_SUBMODULE_STRATEGY: recursive
     REDIS_HOST: redis