Bump pygments from 2.3.1 to 2.7.4

Bumps [pygments](https://github.com/pygments/pygments) from 2.3.1 to 2.7.4.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.3.1...2.7.4)

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

requirements.txt

@@ -15,7 +15,7 @@ nose==1.3.7
 pkginfo==1.5.0.1
 pycodestyle==2.4.0
 pyflakes==2.0.0
-Pygments==2.3.1
+Pygments==2.7.4
 radon==2.2.0
 readme-renderer==24.0
 rednose==1.3.0