Bump matplotlib from 3.10.8 to 3.10.9 in /docs

Bumps [matplotlib](https://github.com/matplotlib/matplotlib) from 3.10.8 to 3.10.9.
- [Release notes](https://github.com/matplotlib/matplotlib/releases)
- [Commits](matplotlib/matplotlib@v3.10.8...v3.10.9)

---
updated-dependencies:
- dependency-name: matplotlib
  dependency-version: 3.10.9
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

docs/requirements.txt

@@ -2,7 +2,7 @@ aiohttp==3.13.3
 autodoc-pydantic==2.2.0
 furo==2025.12.19
 linkify-it-py==2.0.3
-matplotlib==3.10.8
+matplotlib==3.10.9
 myst-nb==1.3.0
 sphinx==8.2.3
 sphinx-click==6.2.0