Bump pygments from 2.9.0 to 2.15.0

Bumps [pygments](https://github.com/pygments/pygments) from 2.9.0 to 2.15.0.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.9.0...2.15.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -10,7 +10,7 @@ mkdocs-material-extensions==1.0.1; python_version >= "3.5"
 mkdocs-material==7.1.9
 mkdocs==1.2.1; python_version >= "3.6"
 packaging==20.9; python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.4.0" and python_version >= "3.6"
-pygments==2.9.0; python_version >= "3.5"
+pygments==2.15.0; python_version >= "3.5"
 pymdown-extensions==8.2; python_version >= "3.6"
 pyparsing==2.4.7; python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.4.0" and python_version >= "3.6"
 python-dateutil==2.8.1; python_version >= "3.6" and python_full_version < "3.0.0" or python_full_version >= "3.3.0" and python_version >= "3.6"