DEPS: increase required version of pygments to 2.7.4

Author: iainrussell

requirements/requirements-docs.txt

@@ -24,7 +24,7 @@ markupsafe==1.0
     # via jinja2
 packaging==17.1
     # via sphinx
-pygments==2.2.0
+pygments>=2.7.4
     # via sphinx
 pyparsing==2.2.0
     # via packaging