Use pyproject.toml instead of envvars for cibuildwheel

[emlowe]

Puts most cibuildwheel configuration into pyproject.toml instead of using envvars in the github actions.

The rationale is that this makes it a little bit easier to build the wheel locally for debugging and testing as there is less configuration specific to GH actions

Note some of the envvars refer to GH action matrix items, so those remain in the GH workflow.

[coveralls-official]

Pull Request Test Coverage Report for Build 5802872593

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 94.649%

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Totals
Change from base Build 5787343810:	0.0%
Covered Lines:	1645
Relevant Lines:	1738

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💛 - Coveralls

[emlowe]

close and re-open for CI

[hoffmang9]

lgtm