Bump mike from 2.1.1 to 2.1.2 in /docs

Bumps [mike](https://github.com/jimporter/mike) from 2.1.1 to 2.1.2.
- [Release notes](https://github.com/jimporter/mike/releases)
- [Changelog](https://github.com/jimporter/mike/blob/master/CHANGES.md)
- [Commits](jimporter/mike@v2.1.1...v2.1.2)

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

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

docs/requirements.txt

@@ -9,7 +9,7 @@ Markdown==3.6
 MarkupSafe==2.1.5
 mdx-truly-sane-lists==1.3
 mergedeep==1.3.4
-mike==2.1.1
+mike==2.1.2
 mkdocs==1.6.0
 mkdocs-exclude==1.0.2
 mkdocs-macros-plugin==1.0.5