corrected yaml syntax for user; reference server.yml in this folder

ntfy/docker-compose.yml

@@ -6,18 +6,12 @@ services:
       - serve
     environment:
       - TZ=America/New_York
-    user: 
+    user: 1000:1000
-      - 1000:1000
     volumes:
       - ./var/cache/ntfy:/var/cache/ntfy
       - ./etc/ntfy:/etc/ntfy
+      - ./server.yml:/etc/ntfy/server.yml
     ports:
       - 4080:80
       - 4443:443
-    networks:
-      - cloudflare_default
     restart: unless-stopped
-
-networks:
-  cloudflare_default:
-    external: true