Installation of ont-pyguppy-client fails for python 3.9

[timp0]

More an FYI than anything, ont-pyguppy-client-lib won't install with pip on python 3.9.2 - which is the default miniconda. Suggest you specify python 3.8 max in documentation.

[marcus1487]

This issue has been raised internally, but a note was added to the README to resolve this issue for now.

It turns out mappy is also not compatible with python 3.9, but I've submitted a MR that was accepted to fix this in the next release.