chore(deps): bump mkdocs-material in /hack/api-docs (#4006)

Bumps [mkdocs-material](https://github.com/squidfunk/mkdocs-material) from 9.5.39 to 9.5.40.
- [Release notes](https://github.com/squidfunk/mkdocs-material/releases)
- [Changelog](https://github.com/squidfunk/mkdocs-material/blob/master/CHANGELOG)
- [Commits](https://github.com/squidfunk/mkdocs-material/compare/9.5.39...9.5.40)

---
updated-dependencies:
- dependency-name: mkdocs-material
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

hack/api-docs/requirements.txt

@@ -18,7 +18,7 @@ mergedeep==1.3.4
 mike @ git+https://github.com/jimporter/mike@300593c338b18f61f604d18457c351e166318020
 mkdocs==1.6.1
 mkdocs-macros-plugin==1.3.5
-mkdocs-material==9.5.39
+mkdocs-material==9.5.40
 mkdocs-material-extensions==1.3.1
 mkdocs-minify-plugin==0.8.0
 packaging==24.1