chore(deps): 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)

---
updated-dependencies:
- dependency-name: pygments
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements_test.txt

@@ -56,7 +56,7 @@ pyflakes==0.8.1
     # via
     #   flake8
     #   hacking
-pygments==2.2.0
+pygments==2.7.4
     # via
     #   -r requirements_test.in
     #   sphinx