python: run isort, add shebangs on all files

tools/README-generator/webhook.py

@@ -1,15 +1,16 @@
-import os
-import hmac
-import shlex
-import hashlib
+#!/usr/bin/env python3
+
 import asyncio
+import hashlib
+import hmac
+import os
+import shlex
 import tempfile
 
+from make_readme import generate_READMEs
 from sanic import Sanic, response
 from sanic.response import text
 
-from make_readme import generate_READMEs
-
 app = Sanic(__name__)
 
 github_webhook_secret = open("github_webhook_secret", "r").read().strip()