Bump packaging from 20.4 to 20.7

Bumps [packaging](https://github.com/pypa/packaging) from 20.4 to 20.7.
- [Release notes](https://github.com/pypa/packaging/releases)
- [Changelog](https://github.com/pypa/packaging/blob/master/CHANGELOG.rst)
- [Commits](pypa/packaging@20.4...20.7)

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

Author: dependabot[bot]

news/requirements.txt

@@ -8,10 +8,9 @@ attrs==19.3.0             # via pytest
 docopt==0.6.2             # via -r news/requirements.in
 iniconfig==1.0.1          # via pytest
 more-itertools==8.0.0     # via pytest
-packaging==20.4           # via pytest
+packaging==20.7           # via pytest
 pluggy==0.13.1            # via pytest
 py==1.9.0                 # via pytest
 pyparsing==2.4.5          # via packaging
 pytest==6.0.1             # via -r news/requirements.in
-six==1.13.0               # via packaging
 toml==0.10.1              # via pytest