Compose: Fix .env.local definition

Imported from https://github.com/rodrigobdz/chat-ui/blob/0c7b33a1bc256baf9b2039ed10f18f427b403c47/compose.yaml#L18-L19.
Discussed in huggingface/chat-ui#1238 (comment).

Author: rodrigobdz

docker-compose-not-working.yml

@@ -15,8 +15,9 @@ services:
     image: ghcr.io/huggingface/chat-ui
     environment:
       MONGODB_URL: mongodb://mongodb:27017
-    env_file: "./.env.local"
+    volumes:
+      - .env.local:/app/.env.local
     ports:
       - "3000"
 volumes:
-  model_data:
+  model_data: