New release to fix tests with scipy

[Mic92]

The latest release is from last october: https://github.com/lmcinnes/umap/releases/tag/0.5.2 However master contains some (test) fixes for newer versions of scipy. Therefore it would be great if we could have a new release. Thanks!

[mjmucha]

Also this f2befed9e9ed1f894beb7fc00d176ce5b76c272d fix for saving / loading models is quite important for me. So a new release would be appreciated!

[lmcinnes]

I'll see what I can manage.