Bump pygments from 2.5.2 to 2.7.4

Bumps [pygments](https://github.com/pygments/pygments) from 2.5.2 to 2.7.4.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.5.2...2.7.4)

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

Author: dependabot[bot]

dev.requirements.txt

@@ -20,7 +20,7 @@ pkginfo==1.5.0.1
 pluggy==0.13.1
 py==1.8.1
 pycparser==2.19
-Pygments==2.5.2
+Pygments==2.7.4
 pyparsing==2.4.6
 pytz==2019.3
 readme-renderer==24.0