Fix the tests

[dannystaple]

Find a way to unit test some parts of this - it may require mocking at the usb library level.

[dannystaple]

See https://github.com/orionrobots/python_usb_robot_arm/blob/main/tests/test_usb_arm.py - seems I already did this 4 years ago.

[dannystaple]

I should probably throw in some github workflows to run it.

[dannystaple]

I had some, with workflows, and broke them by renaming the main branch. Trying to unbreak in PR #21

[dannystaple]

The name is a bit off for the packaging.
usb_arm is a bit generic, as is usb_robot_arm - both are seen here.
Something more specific, involving owi edge maplin maybe...
owi_maplin_usb_arm? I'm not going to rename the repo (right now), but the package can be.