Bump packaging from 16.8 to 19.0
Bump packaging from 16.8 to 19.0

Bumps [packaging](https://github.com/pypa/packaging) from 16.8 to 19.0.
- [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/16.8...19.0)
hughtopping/spektrixpython