Bump isort from 5.9.2 to 5.9.3

Bumps [isort](https://github.com/pycqa/isort) from 5.9.2 to 5.9.3.
- [Release notes](https://github.com/pycqa/isort/releases)
- [Changelog](https://github.com/PyCQA/isort/blob/main/CHANGELOG.md)
- [Commits](PyCQA/isort@5.9.2...5.9.3)

---
updated-dependencies:
- dependency-name: isort
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

requirements-dev.txt

@@ -1,7 +1,7 @@
 -r docs/requirements.txt
 django==3.2.5
 black==21.7b0
-isort==5.9.2
+isort==5.9.3
 flake8==3.9.2
 pydocstyle==6.1.1
 docformatter==1.4