Merge pull request #323 from backstage/renovate/pymdown-extensions-10.x

chore(deps): update dependency pymdown-extensions to v10.21

Author: awanlin

requirements.txt

@@ -14,7 +14,7 @@ markdown-graphviz-inline==1.1.3
 mkdocs-monorepo-plugin==1.1.2
 plantuml-markdown==3.11.1
 mdx_truly_sane_lists==1.3
-pymdown-extensions==10.20.1
+pymdown-extensions==10.21
 pygments==2.19.2
 mkdocs-redirects==1.2.2