Github workflow breaking since Ubuntu 20.04

[rbricheno]

ubuntu-latest was recently changed to 20.04 which makes .github/workflows/test.yml fail for python 3.4.

The failing test reports the error:

Version 3.4 was not found in the local cache
Error: Version 3.4 with arch x64 not found

You can avoid this by either specifying ubuntu-18.04 in your workflow or removing python 3.4 for x64. See here for more information: actions/setup-python#185 (comment)

[Gadgetoid]

Thank you- I've been slowly fixing these as I come across them since this blew up CI across basically all of our libraries. I've been dropping Python 3.4 support. Frustratingly the link to a list of versions given by GitHub Actions when it throws this error clearly includes 3.4, but perhaps I was overlooking the distro differences. Maybe using ubuntu-latest if I want CI not to break spontaneously is a bad idea 😆 - though that said, it's good to revisit these things every now and then.