Bump pygments from 2.7.4 to 2.15.0

Bumps [pygments](https://github.com/pygments/pygments) from 2.7.4 to 2.15.0.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.7.4...2.15.0)

---
updated-dependencies:
- dependency-name: pygments
  dependency-type: direct:production
...

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

requirements.txt

@@ -2,6 +2,6 @@ appdirs==1.4.4
 distlib==0.3.0
 docutils==0.16b0.dev0
 filelock==3.0.12
-Pygments==2.7.4
+Pygments==2.15.0
 six==1.14.0
 virtualenv==20.0.21