Bump mkdocs from 1.2.2 to 1.2.3 (#123)

Bumps [mkdocs](https://github.com/mkdocs/mkdocs) from 1.2.2 to 1.2.3.
- [Release notes](https://github.com/mkdocs/mkdocs/releases)
- [Commits](mkdocs/mkdocs@1.2.2...1.2.3)

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

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Author: dependabot[bot]

poetry.lock

@@ -12,7 +12,7 @@ python-dateutil = "^2.8.1"
 [tool.poetry.dev-dependencies]
 flake8 = "^3.9.2"
 black = "^21.7b0"
-mkdocs = "^1.2.1"
+mkdocs = "^1.2.3"
 mkdocs-material = "^7.2.4"
 mdx-truly-sane-lists = "^1.2"
 GitPython = "^3.1.20"