SIP creates incorrect Python wheel metadata

[Chih-Hsuan Yen]

Hi PyQt developers,

I noticed my PyQt wheel is generated with incorrect metadata. The same
issue occurs in official PyQt wheels, too. For example, in
PyQt6-6.0.2.dist-info/WHEEL from the official PyQt 6.0.2 wheel [1],
there is a line

Root-Is_Purelib: false

The key should be Root-Is-Purelib instead of Root-Is_Purelib [2]. It
seems the incorrect key is from [2].

Such an issue prevents me from installing the wheel using
python-install, which requires Root-Is-Purelib to be present [4].
Could you update sip to use the correct key?

Thanks,

Chih-Hsuan Yen

[1] https://files.pythonhosted.org/packages/49/f6/a447e2ff56416b7b4db4efc9d79d3a28bedeadd2f9074cf45dfd6c89fa96/PyQt6-6.0.2-cp36.cp37.cp38.cp39-abi3-manylinux_2_28_x86_64.whl
[2] https://www.python.org/dev/peps/pep-0427/#file-contents
[3] https://www.riverbankcomputing.com/hg/sip/file/6.0.2/sipbuild/distinfo/distinfo.py#l132
[4] https://github.com/FFY00/python-install/blob/0.0.3/install/__init__.py#L263