sys: remove nonstandard print_exception

[jepler]

CircuitPython provides this at exception.print_exception(), with improved compatibility with standard Python.

This is an alternative to #9427, which adds documentation for the non-standard function.

One reason NOT to take this change is that the traceback module is not built on samd21s, leaving non-standard sys.print_exception as the only way to print an exception object (besides raising it)

[dhalbert]

I looked in the bundle and in the Learn Guide code, and sys.print_exception() is only used in code that runs on larger boards. It is used, so the few places it's used should be fixed to used traceback.

libraries/drivers/mcp2515/examples/mcp2515_canio_test.py
libraries/helpers/debouncer/examples/debouncer_unittest.py

[dhalbert]

I think I am OK with samd21 not being able to print tracebacks "manually". There are so many other things limited in that port, this is not such a big deal. You can still print info about the exception.

[tannewt]

Let's remove in CP10 and add a FutureWarning now because code can be moved to traceback now. (I assume traceback is in 8.x too.)

[jepler]

OK I'll close this up but leave the branch.

[jepler]

Yes it's in 8.2.x https://docs.circuitpython.org/en/8.2.x/shared-bindings/traceback/index.html

[tannewt]

@jepler Can you add the warning? RetiredWizard's PR only updates the docs.

[RetiredWizard]

Great minds think alike.... 😁 #9450