inspect.getargspec code change required for python 3.11

[mdickers47]

Line 231 of pyfirmata2.py calls inspect.getargspec, which was apparently deprecated since at least 2018: pytorch/pytorch#15344

It now doesn't run in python 3.11:

  File "/home/mikey/tmp/pyduino/lib/python3.11/site-packages/pyfirmata2/pyfirmata2.py", line 231, in add_cmd_handler
    len_args = len(inspect.getargspec(func)[0])
                   ^^^^^^^^^^^^^^^^^^
AttributeError: module 'inspect' has no attribute 'getargspec'. Did you mean: 'getargs'?

Changing the line to getfullargspec() seems to solve it.

[mdickers47]

great, thanks!