Update docker-compose to use node:18-alpine image

uptime-bot/docker-compose.yml

@@ -2,9 +2,13 @@ version: '3.8'
 
 services:
   uptime-bot:
-    build: .
+    image: node:18-alpine
     container_name: uptime-bot
     restart: unless-stopped
+    working_dir: /app
+    command: sh -c "npm install && node bot.js"
+    volumes:
+      - ./:/app
     environment:
       - ROCKETCHAT_URL=${ROCKETCHAT_URL:-rocketchat:3000}
       - ROCKETCHAT_USE_SSL=${ROCKETCHAT_USE_SSL:-false}