Kartothek v5.0.0rc1

Version 5.0.0 (2021-05-xx)

This release rolls all the changes introduced with 4.x back to 3.20.0.

As the incompatibility between 4.0 and 5.0 will be an issue for some
customers, we encourage you to use the very stable kartothek 3.20.0 and
not version 4.x.

Please refer the Issue #471 for further information.