Bump packaging from 20.3 to 20.4 (#1728)

Bumps [packaging](https://github.com/pypa/packaging) from 20.3 to 20.4.
- [Release notes](https://github.com/pypa/packaging/releases)
- [Changelog](https://github.com/pypa/packaging/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/pypa/packaging/compare/20.3...20.4)

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

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

requirements.txt

@@ -8,7 +8,7 @@ cryptography==2.9.2
 docker==4.2.0
 gitpython==3.1.2
 jinja2==2.11.2
-packaging==20.3
+packaging==20.4
 ptvsd==4.3.2
 pulsectl==20.4.3
 pytz==2020.1