Bump pygments from 2.2.0 to 2.7.4

Bumps [pygments](https://github.com/pygments/pygments) from 2.2.0 to 2.7.4.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.2.0...2.7.4)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.dev.txt

@@ -15,7 +15,7 @@ tox==3.2.1
 # Sphinx
 MarkupSafe==1.0
 Jinja2==2.10.1
-Pygments==2.2.0
+Pygments==2.7.4
 Sphinx==1.7.7
 
 # qa-all