Bump isort from 4.3.21 to 5.5.1 in /cvat/requirements (#2142)

Bumps [isort](https://github.com/pycqa/isort) from 4.3.21 to 5.5.1.
- [Release notes](https://github.com/pycqa/isort/releases)
- [Changelog](https://github.com/PyCQA/isort/blob/develop/CHANGELOG.md)
- [Commits](https://github.com/pycqa/isort/compare/4.3.21...5.5.1)

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

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

cvat/requirements/development.txt

@@ -1,6 +1,6 @@
 -r base.txt
 astroid==2.4.2
-isort==4.3.21
+isort==5.5.1
 lazy-object-proxy==1.5.1
 mccabe==0.6.1
 pylint==2.6.0