Update the docs dependencies

Author: mdmintz

docs/requirements.txt

@@ -5,6 +5,7 @@ joblib==1.0.1;python_version>="3.6"
 Markdown==3.3.4;python_version>="3.6"
 MarkupSafe==2.0.1;python_version>="3.6"
 docutils==0.17.1
+pkginfo==1.7.1;python_version>="3.6"
 Jinja2==3.0.1;python_version>="3.6"
 click==8.0.1;python_version>="3.6"
 zipp==3.5.0;python_version>="3.6"