Enforce Datetime Type for Expires on Set-Cookie (#1484)

* Enforce Datetime Type for Expires on Set-Cookie

* Fix lint issues

* Format code and improve error type

* Fix import order

tests/test_server_events.py

@@ -83,8 +83,7 @@ async def test_trigger_before_events_create_server(app):
     async def init_db(app, loop):
         app.db = MySanicDb()
 
-    await app.create_server(
-        debug=True, return_asyncio_server=True)
+    await app.create_server(debug=True, return_asyncio_server=True)
 
     assert hasattr(app, "db")
     assert isinstance(app.db, MySanicDb)