tests(comments): use the new Werkzeug API to delete cookies

Since 2.4 [1], Werkzeug deprecated the old `server_name`-based API,
the new way to delete cookies based on server name is to use `domain` kwarg.

This broke NixOS testing of `isso` with our newer dependencies [2].

[1]: https://werkzeug.palletsprojects.com/en/2.3.x/test/#werkzeug.test.Client.delete_cookie
[2]: NixOS/nixpkgs#264081

isso/tests/test_comments.py

@@ -272,7 +272,7 @@ def testFetchAuthorization(self):
         r = self.get('/id/1?plain=1')
         self.assertEqual(r.status_code, 200)
 
-        self.client.delete_cookie('localhost.local', '1')
+        self.client.delete_cookie(key='1', domain='localhost')
         r = self.get('/id/1?plain=1')
         self.assertEqual(r.status_code, 403)