Update requirements.txt dependencies [skip ci]

Author: rfay

requirements.txt

@@ -12,19 +12,19 @@ lunr==0.5.8
 Markdown==3.3.4
 MarkupSafe==1.1.1
 mdx-truly-sane-lists==1.2
-mkdocs==1.2.2
+mkdocs==1.2.3
 mkdocs-git-revision-date-localized-plugin==0.9
-mkdocs-material==7.3.2
+mkdocs-material==7.3.3
 mkdocs-material-extensions==1.0.3
 mkdocs-minify-plugin==0.4.1
-nltk==3.6.4
+nltk==3.6.5
 packaging==20.9
 Pygments==2.8.1
 pymdown-extensions==9.0
 pyparsing==2.4.7
 pytz==2021.1
 PyYAML==5.4.1
-regex==2021.9.30
+regex==2021.10.8
 six==1.15.0
 smmap==4.0.0
 tornado==6.1