Rocrate

* [Methods to add test-related entities](https://github.com/ResearchObject/ro-crate-py/pull/43)
* ["init" mode and first version of a CLI tool](https://github.com/ResearchObject/ro-crate-py/pull/46)
* [Support referring to test suites from the root dataset](https://github.com/ResearchObject/ro-crate-py/pull/55)
* various fixes

Fix requirements list

Adds support for [workflow testing metadata](https://github.com/crs4/life_monitor/wiki/Workflow-Testing-RO-Crate).

This is a bugfix release of RO-Crate-py 0.2

[](https://doi.org/10.5281/zenodo.4269684)

Changelog:
* [Handling of datetimes fixed](https://github.com/ResearchObject/ro-crate-py/pull/37)