Removing heroku support as its no longer free

Procfile

@@ -1 +0,0 @@
-web: python3 ./changedetection.py -C -d ./datastore -p $PORT

app.json

@@ -1,21 +0,0 @@
-{
-  "name": "ChangeDetection.io",
-  "description": "The best and simplest self-hosted open source website change detection monitoring and notification service.",
-  "keywords": [
-    "changedetection",
-    "website monitoring"
-  ],
-  "repository": "https://github.com/dgtlmoon/changedetection.io",
-  "success_url": "/",
-  "scripts": {
-  },
-  "env": {
-  },
-  "formation": {
-    "web": {
-      "quantity": 1,
-      "size": "free"
-    }
-  },
-  "image": "heroku/python"
-}

heroku.yml

@@ -1,2 +0,0 @@
-run:
-  changedetection: python3 ./changedetection.py -C -d ./datastore -p $PORT