chore(deps): bump pygments from 2.17.2 to 2.20.0 in /docs (pybind#6024)

Bumps [pygments](https://github.com/pygments/pygments) from 2.17.2 to 2.20.0.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.17.2...2.20.0)

---
updated-dependencies:
- dependency-name: pygments
  dependency-version: 2.20.0
  dependency-type: indirect
...

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

Author: dependabot[bot]

docs/requirements.txt

@@ -41,7 +41,7 @@ myst-parser==3.0.1
     # via -r requirements.in
 packaging==24.0
     # via sphinx
-pygments==2.17.2
+pygments==2.20.0
     # via
     #   furo
     #   sphinx