Bump isort from 5.6.1 to 5.6.3

Bumps [isort](https://github.com/pycqa/isort) from 5.6.1 to 5.6.3.
- [Release notes](https://github.com/pycqa/isort/releases)
- [Changelog](https://github.com/PyCQA/isort/blob/develop/CHANGELOG.md)
- [Commits](PyCQA/isort@5.6.1...5.6.3)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

tests/requirements.txt

@@ -2,7 +2,7 @@ black==20.8b1
 coverage==5.3
 flake8==3.8.4
 flake8-quotes==3.2.0
-isort==5.6.1
+isort==5.6.3
 mypy==0.782
 pycodestyle==2.6.0
 pyflakes==2.2.0