Updated app.json to use container stack

app.json

@@ -4,14 +4,5 @@
     "repository": "https://github.com/benbusby/shoogle",
     "logo": "https://raw.githubusercontent.com/benbusby/shoogle/master/app/static/img/favicon/ms-icon-150x150.png",
     "keywords": ["search", "metasearch", "flask", "docker", "heroku", "adblock", "degoogle", "privacy"],
-    "image": "heroku/python",
-    "scripts": {
-        "postdeploy": "./run &"
-    },
-    "formation": {
-        "web": {
-            "quantity": 1,
-            "size": "free"
-        }
-    }
+    "stack": "container"
 }