Fix `Role "kemal" does not exist` (#2490)

docker-compose.yml

@@ -12,7 +12,7 @@ services:
       POSTGRES_PASSWORD: kemal
       POSTGRES_USER: kemal
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U $$POSTGRES_USER"]
+      test: ["CMD-SHELL", "pg_isready -U $$POSTGRES_USER $$POSTGRES_DB"]
   invidious:
     build:
       context: .