Bump matplotlib from 3.6.3 to 3.7.2 in /docs

Bumps [matplotlib](https://github.com/matplotlib/matplotlib) from 3.6.3 to 3.7.2.
- [Release notes](https://github.com/matplotlib/matplotlib/releases)
- [Commits](matplotlib/matplotlib@v3.6.3...v3.7.2)

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

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

docs/requirements.txt

@@ -4,4 +4,4 @@ sphinx-click==4.1.0
 myst_parser==0.17.2
 ghostscript==0.7
 opencv-python==4.7.0.68
-matplotlib==3.6.3
+matplotlib==3.7.2