- Update description

- New upstream release 1.6.0
* Improve error message for invalid markers (#569).
* Increase robustness when deleting temporary directories on
Windows (#460).
* Replace tomlkit with tomli, which changes the interface of some
internal classes (#483).
* Deprecate Package.category (#561).
* Fix a performance regression in marker handling (#568).
* Fix an issue where wildcard version constraints were not
handled correctly (#402).
* Fix an issue where poetry build created duplicate Python
classifiers if they were specified manually (#578).
* Fix an issue where local versions where not handled correctly
(#579).