Update python requirements

requirements.txt

 backports-abc==0.5
-Click==7.0
+Click==7.1.1
 EditorConfig==0.12.2
-futures==3.2.0
-Jinja2==2.10
-jsbeautifier==1.9.0
-livereload==2.6.0
-Markdown==3.0.1
+futures==3.3.0
+Jinja2==2.11.1
+jsbeautifier==1.10.3
+livereload==2.6.1
+Markdown==3.1.1
 MarkupSafe==1.1.1
 mkdocs==1.0.4
-mkdocs-material==4.0.1
-Pygments==2.3.1
-pymdown-extensions==6.0
-PyYAML==3.13
+mkdocs-material==4.6.0
+Pygments==2.5.2
+pymdown-extensions==6.2.1
+PyYAML==5.3.1
 singledispatch==3.4.0.3
-six==1.12.0
+six==1.14.0
 tornado==5.1.1