Bump mkdocstrings[python] from 0.19.0 to 0.20.0 in /docs/user (#250)

Bumps [mkdocstrings[python]](https://github.com/mkdocstrings/mkdocstrings) from 0.19.0 to 0.20.0.
- [Release notes](https://github.com/mkdocstrings/mkdocstrings/releases)
- [Changelog](https://github.com/mkdocstrings/mkdocstrings/blob/master/CHANGELOG.md)
- [Commits](mkdocstrings/mkdocstrings@0.19.0...0.20.0)

---
updated-dependencies:
- dependency-name: mkdocstrings[python]
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

docs/user/requirements.txt

@@ -1,6 +1,6 @@
 mkdocs==1.4.0
 mkdocs-material==8.5.6
-mkdocstrings[python]==0.19.0
+mkdocstrings[python]==0.20.0
 mkdocstrings-python==0.7.1
 markdown-include==0.6.0
 mkdocs-gen-files==0.4.0