Python 3.9 support

[laike9m]

It seems azure pipeline has added support for Python 3.9 (not 100% sure), so opening an issue here as well.

actions/runner-images#1740

[gaborbernat]

Addressed with 5618f96

[gaborbernat]

Well, we added support for it, but seems Azure is still lacking compared to Github Actions:

Versions in /opt/hostedtoolcache:

2.7.18 (x64)
3.5.10 (x64)
3.6.12 (x64)
3.7.9 (x64)
3.8.6 (x64)
If this is a Microsoft-hosted agent, check that this image supports side-by-side versions of Python at https://aka.ms/hosted-agent-software

[laike9m]

That's too bad...but thanks for the quick response

[laike9m]

Can we reopen this? According to this and this, Python 3.9 should already be supported on Windows and Mac.

[gaborbernat]

Addressed 30f07f8