Update markdown from 3.3.4 to 3.3.6

Author: pyup-bot

requirements/pip.txt

@@ -68,7 +68,7 @@ Unipath==1.1
 django-kombu==0.9.4
 stripe==2.63.0
 regex==2021.11.10
-markdown==3.3.4
+markdown==3.3.6
 
 # unicode-slugify==0.1.5 is not released on PyPI yet
 git+https://github.com/mozilla/unicode-slugify@b696c37#egg=unicode-slugify==0.1.5