Bump pygments from 2.17.2 to 2.18.0 in /docs (#918)

Bumps [pygments](https://github.com/pygments/pygments) from 2.17.2 to 2.18.0.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.17.2...2.18.0)

---
updated-dependencies:
- dependency-name: pygments
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

docs/requirements.txt

@@ -3,4 +3,4 @@ mkdocs-macros-plugin==1.0.5
 mkdocs-awesome-pages-plugin==2.9.2
 mkdocs-exclude==1.0.2
 mdx-breakless-lists==1.0.1
-pygments==2.17.2
+pygments==2.18.0