Drop support for python 3.9

[egillax]

I think we should drop support for python 3.8 and 3.9. These have reached end of life (no security fixes applied anymore).

[egillax]

Dropped support for 3.8 in #17 , will keep support for 3.9 for an ongoing env requiring it.

Note @azimov , python 3.9 is end of life since end of last year: https://devguide.python.org/versions/#full-chart

[azimov]

@egillax - I just have a single linux box within jnj that runs python 3.9. So we can have it on the roadmap to drop support