Bump gitpython from 3.0.8 to 3.1.3 in /cvat/requirements (#1698)

Bumps [gitpython](https://github.com/gitpython-developers/GitPython) from 3.0.8 to 3.1.3.
- [Release notes](https://github.com/gitpython-developers/GitPython/releases)
- [Changelog](https://github.com/gitpython-developers/GitPython/blob/master/CHANGES)
- [Commits](https://github.com/gitpython-developers/GitPython/compare/3.0.8...3.1.3)

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Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

cvat/requirements/base.txt

@@ -24,7 +24,7 @@ dj-pagination==2.4.0
 python-logstash==0.4.6
 django-revproxy==0.9.15
 rules==2.0
-GitPython==3.0.8
+GitPython==3.1.3
 coreapi==2.3.3
 django-filter==2.0.0
 Markdown==3.2.2