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

@@ -8,7 +8,7 @@ colorama>=0.3.7 # note: on windows click requires colorama too http://click.poco
 pyparsing>=2.1.10
 jinja2>=3.1.2 # for gendocs
 jinja2-time>=0.2.0 # for gendocs
-pygments==2.7.4 # for gendocs
+pygments==2.15.0 # for gendocs
 
 # readline==6.2.4.1  # optional, for shell autocomplete