Allow pyparsing>3.0 and minor cleanup

[bsilvereagle]

Allow pyparsing>3.0 (backwards compatible)

Using tip of tree plyse with pyparsing >=3.0 causes errors due to operatorPrecedence being renamed to infixNotation and ParsingElement.name to ParsingElement.customName.

Test fixes

grammar_from_config_test.py used a local import that was not resolving.

setup.py cleanup

python_requires in setup.py is not respected

Pinned pyparsing to be less than today's version, 3.1.1.

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Tests

All tests passing in plyse/plyse/tests with Python 3.11.2 and pyparsing '2.4.7' and '3.1.1'

[kaktus42]

any chance we can get this merged?
Thanks for the effort, @bsilvereagle