Merge #214

214: Update packaging to 20.5 r=duckinator a=pyup-bot


This PR updates [packaging](https://pypi.org/project/packaging) from **20.4** to **20.5**.



<details>
  <summary>Changelog</summary>
  
  
   ### 20.5
   ```
   ~~~~~~~~~~~~~~~~~

* Officially support Python 3.9 (:issue:`343`)
* Deprecate the ``LegacyVersion`` and ``LegacySpecifier`` classes (:issue:`321`)
* Handle ``OSError`` on non-dynamic executables when attempting to resolve
  the glibc version string.
   ```
   
  
</details>


 

<details>
  <summary>Links</summary>
  
  - PyPI: https://pypi.org/project/packaging
  - Changelog: https://pyup.io/changelogs/packaging/
  - Repo: https://github.com/pypa/packaging
</details>



Co-authored-by: pyup-bot <github-bot@pyup.io>

setup.cfg

@@ -27,7 +27,7 @@ python_requires = >=3.6
 # The importlib_metadata library is required by Twine for Python 3.7 and
 # earlier, but we pull it in unconditionally so the zipapp is version-agnostic.
 install_requires =
-    packaging==20.4
+    packaging==20.5
     toml==0.10.2
     pep517==0.8.2
     twine==3.2.0