Bump pygments from 2.15.0 to 2.18.0 in /docs

Bumps [pygments](https://github.com/pygments/pygments) from 2.15.0 to 2.18.0.
- [Release notes](https://github.com/pygments/pygments/releases)
- [Changelog](https://github.com/pygments/pygments/blob/master/CHANGES)
- [Commits](pygments/pygments@2.15.0...2.18.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

docs/requirements.txt

@@ -7,7 +7,7 @@ idna==3.10
 imagesize==1.4.1
 Jinja2==3.1.4
 MarkupSafe==2.1.5
-Pygments==2.15.0
+Pygments==2.18.0
 pytz==2024.2
 requests==2.32.3
 six==1.16.0