chore(gh): update mkdocs-markdownextradata-plugin requirement

Updates the requirements on [mkdocs-markdownextradata-plugin](https://github.com/rosscdh/mkdocs-markdownextradata-plugin) to permit the latest version.
- [Release notes](https://github.com/rosscdh/mkdocs-markdownextradata-plugin/releases)
- [Commits](rosscdh/mkdocs-markdownextradata-plugin@0.2.5...0.2.6)

---
updated-dependencies:
- dependency-name: mkdocs-markdownextradata-plugin
  dependency-version: 0.2.6
  dependency-type: direct:production
...

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

Author: dependabot[bot]

docs/requirements.txt

@@ -1,4 +1,4 @@
 mkdocs-git-revision-date-localized-plugin >= 1.2.2
-mkdocs-markdownextradata-plugin >= 0.2.5
+mkdocs-markdownextradata-plugin >= 0.2.6
 mkdocs-minify-plugin>=0.7.2
 mkdocs-open-in-new-tab>=1.0.8