Fix invalid overrides of mistune methods

[quis]

When overriding a method the type signature (including the names of arguments should be the same).

This commit fixes warnings like these emitted by a type checker:

error[invalid-method-override]: Invalid override of method `link`
   --> notifications_utils/markdown.py:126:9
    |
126 |     def link(self, link, title, content):
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `Renderer.link`
    |
   ::: /Users/chris.hill-scott/.pyenv/versions/3.13.2/envs/notifications-utils-3.13/lib/python3.13/site-packages/mistune.py:879:9
    |
879 |     def link(self, link, title, text):
    |         ----------------------------- `Renderer.link` defined here
    |