Merge pull request #434 from Yelp/dependabot/pip/urllib3-1.26.3

Bump urllib3 from 1.26.2 to 1.26.3

Author: domanchi

requirements-dev.txt

@@ -37,6 +37,6 @@ tox-pip-extensions==1.6.0
 typed-ast==1.4.1
 typing-extensions==3.7.4.3
 unidiff==0.6.0
-urllib3==1.26.2
+urllib3==1.26.3
 virtualenv==20.2.1
 zipp==3.4.0