title: Issue with Flask-Sitemap after upgrading to python3.10
body: <p>I've just updated my python version to 3.10 and received following error:</p>
  <pre><code>from flask_sitemap import Sitemap
  /usr/local/lib/python3.10/site-packages/flask_sitemap/__init__.py:32: in &lt;module&gt;
  from collections import Mapping
  E   ImportError: cannot import name 'Mapping' from 'collections' (/usr/local/lib/python3.10/collections/__init__.py)
  </code></pre>