Use isinstance in builtin crc32

[FlxB2]

I'm in the process of building a dynamic analysis tool for python, I ran it on this repo and found a potential improvement.

Right now the builtin crc32 module uses type(data) != array.array.
However, using not isinstance(data, array.array) has a number of advantages:

• array.array subtypes are supported
• follows PEP-008 recommendations
• better readability
• performance improvement

I measured the performance as follows:

$ python3.9 -m timeit -s "from _crc32c import crc_update_faster; import array" -u nsec "crc_update_faster(0, array.array('B', b''))"
500000 loops, best of 5: 576 nsec per loop
$ python3.9 -m timeit -s "from _crc32c import crc_update; import array" -u nsec "crc_update(0, array.array('B', b''))"
500000 loops, best of 5: 622 nsec per loop
$ python3.9 --version
Python 3.9.14

where crc_update_faster uses not isinstance(data, array.array).

You can find a more detailed explanation why isinstance might be better in this blogpost.

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This change is 

[wbarnha]

Thanks for profiling this! Using isinstance for checks is always a good choice.