Bump pygments from 2.1.3 to 2.7.4

Bumps [pygments](https://github.com/pygments/pygments) from 2.1.3 to 2.7.4.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.1.3...2.7.4)

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

requirements-old.txt

@@ -108,7 +108,7 @@ pycosat==0.6.1
 pycrypto==2.6
 pydot==1.0.28
 pygit==0.1
-Pygments==2.1.3
+Pygments==2.7.4
 pylint==0.25.1
 pymemcache==3.4.1
 pyparsing==2.0.2