Port to py3.7 +

[goodboy]

As part of this moving to github actions might be in order (since apparently that's what everyone is doing and I do like msft footing the bill).

Has anyone done any ports already?

If so please please please send us a PR 😹

[kontsaki]

i'm running under 3.7 and 3.8 just fine btw :)

i may take a look at github actions to help push this.

[goodboy]

@kontsaki you would be my best pysipp pal then 😸