chore(gh): update mkdocs-markdownextradata-plugin requirement from >=0.2.5 to >=0.2.6 (#284)

Updates the requirements on
[mkdocs-markdownextradata-plugin](https://github.com/rosscdh/mkdocs-markdownextradata-plugin)
to permit the latest version.
<details>
<summary>Commits</summary>
<ul>
<li><a
href="https://github.com/rosscdh/mkdocs-markdownextradata-plugin/commit/f3cd07534853bf11e8bf05fcd097fde20b5060ca"><code>f3cd075</code></a>
added contributers and bump</li>
<li><a
href="https://github.com/rosscdh/mkdocs-markdownextradata-plugin/commit/59bb1888f637fc9a821bb4d3d6c2ba1b472b75f2"><code>59bb188</code></a>
added contributers</li>
<li><a
href="https://github.com/rosscdh/mkdocs-markdownextradata-plugin/commit/23eea4aa65971b33c3718fef08ccd8cb2f84b7dd"><code>23eea4a</code></a>
migrate to gh actions, add tests and publish wheel (<a
href="https://redirect.github.com/rosscdh/mkdocs-markdownextradata-plugin/issues/44">#44</a>)</li>
<li><a
href="https://github.com/rosscdh/mkdocs-markdownextradata-plugin/commit/ed92246307da18e3fc3bee841d7ad090f14ddca2"><code>ed92246</code></a>
Remove warnings_filter (<a
href="https://redirect.github.com/rosscdh/mkdocs-markdownextradata-plugin/issues/51">#51</a>)</li>
<li>See full diff in <a
href="https://github.com/rosscdh/mkdocs-markdownextradata-plugin/compare/0.2.5...0.2.6">compare
view</a></li>
</ul>
</details>
<br />

Author: nathanthaler

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