Bump gitpython from 3.1.35 to 3.1.37 in /docs (#415)

Bumps [gitpython](https://github.com/gitpython-developers/GitPython) from 3.1.35 to 3.1.37.
- [Release notes](https://github.com/gitpython-developers/GitPython/releases)
- [Changelog](https://github.com/gitpython-developers/GitPython/blob/main/CHANGES)
- [Commits](gitpython-developers/GitPython@3.1.35...3.1.37)

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

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Author: dependabot[bot]

docs/requirements.txt

@@ -1,6 +1,6 @@
 doc8==0.10.1
 docutils==0.16.0
-GitPython==3.1.35
+GitPython==3.1.37
 setuptools==65.5.1
 sphinx_rtd_theme==0.5.2
 sphinx-tabs==3.2.0