Update python versions in actions

[liaochris]

@jmshapir Python 3.9 is still part of our test environment but reached end of life in October of this year. I think that might be why our actions failed when merging into main even though they didn't fail in the pull.

In this issue, I will remove Python 3.9 and look into adding later Python versions.

[liaochris]

Conversation continues in #138

[liaochris]

In this issue, I updated the python versions supported by the template and replaced platform mocking with skipping OS-specific unit tests when the unit test OS and system OS do not align.

latest version of branch

branch merged in 73fefa0