chore(deps): bump mkdocs from 1.0.4 to 1.2.3 in /docs

Bumps [mkdocs](https://github.com/mkdocs/mkdocs) from 1.0.4 to 1.2.3.
- [Release notes](https://github.com/mkdocs/mkdocs/releases)
- [Commits](mkdocs/mkdocs@1.0.4...1.2.3)

---
updated-dependencies:
- dependency-name: mkdocs
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

docs/requirements.txt

@@ -1,4 +1,4 @@
-mkdocs==1.0.4
+mkdocs==1.2.3
 mkdocs-material==4.4.3
 pymdown-extensions==6.1
 Pygments==2.4.2