Add tests for pokeys_py component

[zarfld]

Related to #31

Add comprehensive tests for pokeys_py component covering various functionalities.

• Peripheral Devices Tests:

  • Add tests/test_peripheral_devices.py to test PoNETkbd48CNC, PoExtBusOC16, and PoRelay8.
  • Use mocking to simulate device responses.
  • Verify correct interaction with peripheral devices.

• CAN Bus Communication Tests:

  • Add tests/test_can_bus.py to test CAN bus communication.
  • Use mocking to simulate CAN bus responses.
  • Verify correct data exchange over CAN bus.

• Digital I/O Inversion Tests:

  • Add tests/test_digital_io_inversion.py to test handling inversion parameters in digital I/O.
  • Verify correct inversion behavior for digital inputs and outputs.
  • Use mocking to simulate device responses.

• Documentation Update:

  • Update README.md with instructions for running new tests.
  • Include details on interpreting test results.
  • Add information about hardware-dependent tests.

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