Bump pygments from 2.6.1 to 2.7.4

Bumps [pygments](https://github.com/pygments/pygments) from 2.6.1 to 2.7.4.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.6.1...2.7.4)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -34,7 +34,7 @@ ptyprocess==0.6.0
 py==1.8.0
 pycparser==2.20
 pygit2==1.5.0
-Pygments==2.6.1
+Pygments==2.7.4
 pyparsing==2.4.5
 pytest==5.3.2
 django-widget-tweaks==1.4.8