replace with literals

.gitlab-ci.yml

@@ -5,10 +5,10 @@ services:
 
 variables:
   TEST_DB_NAME: test
-  POSTGRES_DB: $POSTGRES_DB
+  POSTGRES_DB: fahrtenbuch
   POSTGRES_HOST: postgres
-  POSTGRES_USER: $POSTGRES_USER
-  POSTGRES_PASSWORD: $POSTGRES_PASSWORD
+  POSTGRES_USER: postgres
+  POSTGRES_PASSWORD: postgres
   POSTGRES_HOST_AUTH_METHOD: trust
   POSTGRES_DRIVER: postgres
   SKIP_PREFLIGHT_CHECK: "true"