Fix typo in path for Postgres data volume

This commit fixes an issue with the docker-compose.prod.yml file where we were mounting the data volume on the wrong path within the container.

Author: Keith Thompson

docker-compose.prod.yml

@@ -23,7 +23,7 @@ services:
     image: postgres
     env_file: .env.prod
     volumes:
-      - db-data:/var/lib/postgresql/db-data
+      - db-data:/var/lib/postgresql/data
     ports:
       - "5432:5432"