Support Python 3.12

[kwabenantim]

Summary

The stable and supported versions of Python are currently 3.8 to 3.12.

What’s New In Python 3.12

[kwabenantim]

test_jacobian fails when comparing equations due to differences in printing OrderedDict between Python 3.11 and 3.12. python/cpython#101446

In Python 3.11 the output is a list of (key, value) tuples:

OrderedDict([('lhs', 'x0'), ('rhs', 'x0120.0*_sodium_channel_m_gate$m**3.0'), ('sympy_lhs', x0)])

In Python 3.12 the output is a dictionary:

OrderedDict({'lhs': 'x0', 'rhs': 'x0120.0*_sodium_channel_m_gate$m**3.0', 'sympy_lhs': x0})

[kwabenantim]

pkg_resources is deprecated in Python 3.12: mu-editor/mu#2485

[bdevans]

It's a good time to remove instances of OrderedDict and change them to standard dict instances since they have respected insertion order since Python 3.6.

[kwabenantim]

Thanks @bdevans. That seems like a good approach as we only support Python 3.6+. It's guaranteed to work with all Python interpreters from 3.7 and CPython from 3.6 [1] [2] but I think we only need to worry about CPython.