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] <support@github.com>

requirements.txt

@@ -18,7 +18,7 @@ pluggy==0.6.0
 py==1.5.3
 pycodestyle==2.3.1
 pyflakes==1.6.0
-Pygments==2.2.0
+Pygments==2.7.4
 pyparsing==2.2.0
 pytz==2018.4
 requests==2.18.4