chore(docker): Pull the published image instead of building locally

Use the ghcr.io image built and published by CI rather than a local
docker build context.

docker-compose.yml

@@ -1,8 +1,6 @@
 services:
   prayertimes:
-    build:
-      context: .
-      dockerfile: Dockerfile
+    image: ghcr.io/abdusco/prayertimes:latest
     container_name: prayertimes
     ports:
       - "8000:8000"