Bump packaging from 21.0 to 21.3

Bumps [packaging](https://github.com/pypa/packaging) from 21.0 to 21.3.
- [Release notes](https://github.com/pypa/packaging/releases)
- [Changelog](https://github.com/pypa/packaging/blob/main/CHANGELOG.rst)
- [Commits](pypa/packaging@21.0...21.3)

---
updated-dependencies:
- dependency-name: packaging
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

requirements-dev.txt

@@ -1,6 +1,6 @@
 -r requirements-test.txt
 black==21.12b0
-packaging==21.0
+packaging==21.3
 pre-commit~=2.15
 PyGithub~=1.54
 pyupgrade~=2.31