Use new create package action with attestation

[rmartin16]

Changes

• Implement Implement hynek/build-and-inspect-python-package in python-package-create.yml .github#137
• Run check-wheel-contents during tox -e package
• Ensure package is attested during release
• Remove tox -e package target

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[rmartin16]

Toga has a unique complication the other repos didn't have. All of the other repos just include the sdist and wheel in the artifact....but Toga would replicate the internal filesystem structure of the repo such that the individual sdists and wheels were actually nested inside their respective subdirectory and dist dirs inside the artifact. Therefore, previously, when the artifacts were unpacked, the sdists and wheels would end up in dist directories inside the subdirectories. Now, all of the sdists and wheels are just unpacked in to a top-level dist directory since the new action couldn't replicate the old behavior. FWIW, the release/publish workflow had already implemented its own shenanigans to deal with this previously.

[rmartin16]

Testbed on macOS x86 is consistently failing....

https://github.com/beeware/toga/actions/runs/9277895431/job/25528491914?pr=2604

[freakboy3742]

👍