Bump packaging from 20.1 to 20.4

Bumps [packaging](https://github.com/pypa/packaging) from 20.1 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/20.1...20.4)

requirements.txt

@@ -14,7 +14,7 @@ numpy==1.18.1
 outlier==0.2
 utils==1.0.1
 outlier-utils==0.0.3
-packaging==20.1
+packaging==20.4
 pandas==1.0.1
 pluggy==0.13.1
 py==1.8.1