Merge pull request #78 from ecmwf/dependabot/pip/requirements/pygments-2.20.0

Bump pygments from 2.18.0 to 2.20.0 in /requirements

Author: iainrussell

requirements/requirements-docs.txt

@@ -24,7 +24,7 @@ markupsafe==2.1.5
     # via jinja2
 packaging==17.1
     # via sphinx
-pygments==2.18.0
+pygments==2.20.0
     # via sphinx
 pyparsing==2.2.0
     # via packaging