Update cryptography to version 39

[mhsmith]

Fixes #657.

This requires too many manual actions to be merged in its current state. See #1030 for a way forward.

Related:

• cryptography beeware/mobile-forge#3

[IsakTheHacker]

What is the status of this PR? I really need Cryptography 36.0.2 or newer

[mhsmith]

This PR still needs to be cleaned up as described in the top comment, but there are some some pre-built wheels at https://github.com/emanuele-f/chaquopy-wheels. I haven't tested these wheels myself, so you should only use them for sensitive work if you trust @emanuele-f.

[IsakTheHacker]

Yes, I know there are prebuilt wheels and that you can also just build them yourself (which I am currently doing). But this makes it really hard to set up automated testing and building on a CI. Could you please consider looking into fixing what needs to be cleaned up? Or just merging as is since the issues doesn't seem to bad

[mhsmith]

Sorry, it's not clean enough to merge, and I don't have time to look into the issues right now. But using wheels from an unofficial source is not that hard: just follow the instructions here. You could even copy the wheels into your app's own repository if you like.

[mhsmith]

Replaced by #1261.