Bump packaging from 20.9 to 21.0

Bumps [packaging](https://github.com/pypa/packaging) from 20.9 to 21.0.
- [Release notes](https://github.com/pypa/packaging/releases)
- [Changelog](https://github.com/pypa/packaging/blob/main/CHANGELOG.rst)
- [Commits](pypa/packaging@20.9...21.0)

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

Author: dependabot-preview[bot]

poetry.lock

@@ -32,7 +32,7 @@ classifiers = [
 python = "^3.6"
 
 coverage = "^5.0"
-packaging = "^20.4"
+packaging = ">=20.4,<22.0"
 
 
 [tool.poetry.dev-dependencies]