Refresh mkdocs dependencies

Author: mdmintz

mkdocs_build/requirements.txt

@@ -14,14 +14,14 @@ click==8.1.3
 ghp-import==2.1.0
 readme-renderer==37.3
 pymdown-extensions==9.11
-importlib-metadata==6.3.0
+importlib-metadata==6.4.1
 pipdeptree==2.7.0
 bleach==6.0.0
 lunr==0.6.2
 nltk==3.8.1
 tornado==6.2
 watchdog==3.0.0
-cairocffi==1.5.0
+cairocffi==1.5.1
 cairosvg==2.7.0
 cssselect2==0.7.0
 tinycss2==1.2.1