refactor: use Rust 1.77.0 support for recursion in async functions

[link2xt]

Postponed at least until GitHub actions runners are updated to 1.77.0. We also need to bump toolchains used to build Android and iOS to 1.77 first.

[r10s]

We also need to bump toolchains used to build Android and iOS to 1.77 first.

• i did a PR for iOS at bump rust to 1.77 deltachat-ios#2123 that works after a lipo update
• for android, your PR Update to Rust 1.77 deltachat-android#2983 works for me as well

maybe wait until @zeitschlag and @adbenitez confirm that things work for them as well, but in general, it looks good :)

[link2xt]

1.77 is not in the runner images, but promised in the next update: actions/runner-images#9547 (comment)

[link2xt]

macos-latest runners still have Rust 1.76. Badge at https://github.com/actions/runner-images says "deploying", once it is deployed we should have Rust 1.77 there.