Test many different encodings

[StanFromIreland]

No description provided.

[StanFromIreland]

This is interesting, even on Ubuntu in the CI we create a codec object for unsupported codecs:

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FAIL: test_available_encodings (test_iconvcodec.TestIconvcodecModule.test_available_encodings) (encoding='Georgian-PS')
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Traceback (most recent call last):
  File "/home/runner/work/python-iconv/python-iconv/test_iconvcodec.py", line 95, in test_available_encodings
    raise AssertionError(
        f"Codec lookup succeeded but encode failed for '{encoding}'"
    ) from None
AssertionError: Codec lookup succeeded but encode failed for 'Georgian-PS'

======================================================================
FAIL: test_available_encodings (test_iconvcodec.TestIconvcodecModule.test_available_encodings) (encoding='ARMSCII-8')
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/runner/work/python-iconv/python-iconv/test_iconvcodec.py", line 95, in test_available_encodings
    raise AssertionError(
        f"Codec lookup succeeded but encode failed for '{encoding}'"
    ) from None
AssertionError: Codec lookup succeeded but encode failed for 'ARMSCII-8'

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[StanFromIreland]

I suggest we switch, VISCII is not provided by CPython, and seems to be more cross-platform than T.61.

[bodograumann]

Why not use self.fail here as well?