Bump mkdocs-material-extensions from 1.2 to 1.3 in /docs

Bumps [mkdocs-material-extensions](https://github.com/facelessuser/mkdocs-material-extensions) from 1.2 to 1.3.
- [Release notes](https://github.com/facelessuser/mkdocs-material-extensions/releases)
- [Changelog](https://github.com/facelessuser/mkdocs-material-extensions/blob/master/changelog.md)
- [Commits](facelessuser/mkdocs-material-extensions@1.2...1.3)

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

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

docs/requirements.txt

@@ -14,7 +14,7 @@ mkdocs==1.5.3
 mkdocs-exclude==1.0.2
 mkdocs-macros-plugin==1.0.4
 mkdocs-material==9.4.6
-mkdocs-material-extensions==1.2
+mkdocs-material-extensions==1.3
 packaging==23.2
 Pygments==2.16.1
 pymdown-extensions==10.3