build(deps): bump pygments from 2.15.0 to 2.20.0 (#583)

Bumps [pygments](https://github.com/pygments/pygments) from 2.15.0 to 2.20.0.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.15.0...2.20.0)

---
updated-dependencies:
- dependency-name: pygments
  dependency-version: 2.20.0
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements-docs.txt

@@ -9,7 +9,7 @@ imagesize==1.1.0
 Jinja2==3.1.6
 MarkupSafe==1.1.1
 packaging==19.1
-Pygments==2.15.0
+Pygments==2.20.0
 pyparsing==2.4.2
 pytz==2019.2
 requests==2.32.4