Update mkdocstrings[python] requirement from ==0.27.* to ==0.29.*

Updates the requirements on [mkdocstrings[python]](https://github.com/mkdocstrings/mkdocstrings) to permit the latest version.
- [Release notes](https://github.com/mkdocstrings/mkdocstrings/releases)
- [Changelog](https://github.com/mkdocstrings/mkdocstrings/blob/main/CHANGELOG.md)
- [Commits](mkdocstrings/mkdocstrings@0.27.0...0.29.1)

---
updated-dependencies:
- dependency-name: mkdocstrings[python]
  dependency-type: direct:development
...

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

Author: dependabot[bot]

requirements/dev.txt

@@ -4,7 +4,7 @@ bump2version ==1.0.1
 mkdocs-material ==9.5.*
 ipython[notebook] >8.0, <9.0
 mkdocstrings[python] ==0.26.*; python_version < "3.9"
-mkdocstrings[python] ==0.27.*; python_version >= "3.9"
+mkdocstrings[python] ==0.29.*; python_version >= "3.9"
 mknotebooks ==0.8.*
 pytest >=5.3.2
 pytest-runner >=5.1