Bump pygments from 2.4.0 to 2.7.4 in /python-ff

Bumps [pygments](https://github.com/pygments/pygments) from 2.4.0 to 2.7.4.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.4.0...2.7.4)

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

Author: dependabot[bot]

python-ff/requirements.txt

@@ -63,7 +63,7 @@ protobuf==3.7.1
 psutil==5.6.1
 ptyprocess==0.6.0
 pycocotools==2.0.0
-Pygments==2.4.0
+Pygments==2.7.4
 pyparsing==2.4.0
 pyrsistent==0.15.1
 python-dateutil==2.8.0