Sgkit

This is a major release of sgkit, with support for the [VCF Zarr specification](https://github.com/pystatgen/vcf-zarr-spec/blob/main/vcf_zarr_spec.md).

[Issues closed since 0.4.0](https://github.com/pystatgen/sgkit/issues?q=is%3Aissue+is%3Aclosed+closed%3A2021-11-18..2022-04-07+)

Documentation for this release is at https://pystatgen.github.io/sgkit/0.5.0/

This is the second major release of sgkit.

[Issues closed since 0.3.0](https://github.com/pystatgen/sgkit/issues?q=is%3Aissue+is%3Aclosed+closed%3A2021-08-02..2021-11-16+)

Documentation for this release is at https://pystatgen.github.io/sgkit/0.4.0/

This is the first non-alpha release of sgkit.

Documentation is at https://pystatgen.github.io/sgkit/0.3.0/