Update the year in copyright

YDX-2147483647 · waylan · commit 4a7b9352d677 · 2023-01-09T09:21:53.000-05:00
It's 2023 now.
diff --git a/mkdocs.yml b/mkdocs.yml
@@ -2,7 +2,7 @@ site_name: Python-Markdown
 site_url: https://Python-Markdown.github.io/
 repo_url: https://github.com/Python-Markdown/markdown
 site_author: "The Python-Markdown Project"
-copyright: "Copyright &copy; 2010-2017"
+copyright: "Copyright &copy; 2010-2023"
 
 use_directory_urls: true
 
