Add support for Python 3.13

[freakboy3742]

Python 3.13 finalised the "dead batteries" deprecations, so there are some modules that no longer exist.

Temporarily disabling the binary modules so that the 3.13 tests will pass.

This also drops Python 3.8 support, and makes some minor project format changes for recent Briefcase releases.

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

[freakboy3742]

See the Briefcase PR for details on the merge strategy for this template change.

[mhsmith]

We do now have 3.12 Android wheels for Pillow and NumPy, so I guess that doesn't need to be excluded.

On 3.13 we don't have wheels for iOS either, so is the plan to exclude iOS as well, or to hold off merging this PR until you've built them?

[freakboy3742]

Good catch on the Android 3.12 exclusion; that exists because I originally wrote this PR late last year before 3.12 support landed in Chaquopy.

As for other platforms - we need to exclude binaries on all iOS versions because of the change in binary tag from the 3.13 backport; and we need to exclude numpy and pandas from all platforms on 3.13 specifically because there aren't 3.13 wheels yet. We can drop the "!= iOS" exclusion once I've updated mobile-forge et al and have published new wheels.

[freakboy3742]

Looks like we're still missing binary packages on Android for Cryptography on 3.11 and 3.12, though.

[mhsmith]

Chaquopy issue:

• cryptography for Python 3.11 or later chaquo/chaquopy#1175

[freakboy3742]

I've reverted the changes related to Android; this PR is now "no worse than it was before" regarding Android support. When wheels for Cryptography on 3.11+ are available, we can push an update to - at this point, we might as well wait until we have full 3.13 support for Android.

Binary package support for iOS has also been removed; again, we can restore that in a separate PR once the wheels are available.