Bump MSRV to 1.85

[spacebear21]

The BDK and LDK projects are bumping their MSRV's to keep up with rustls security patches.

In our case, we don't depend on rustls unless the _danger_local_https flag is enabled, but it may be desirable to keep up with the rest of the ecosystem. It may be a while until rust-bitcoin follows suit.

[benalleng]

What are some current TODOs or compromises we have made that we can improve upon with a bump to msrv?

[spacebear21]

In recent memory:

• Prevents us from upgrading testcontainers which would immediately solve the redis/docker flakiness in dart tests.
• Potentially prevents us from transitioning to bitcoind-async-client (see discussion on Replace bitcoincore-rpc with custom reqwest client #945).
• Fix incompatible_msrv_exceptions clippy warnings #794
• Generally prevents us from using nice newer Rust features and syntax (std::cell::OnceCell, is_some_and(), is_err_and(), async fn in traits, etc.)

[DanGould]

Debian stable was the bottleneck and the linked BDK issue says that'll support 1.85 this coming week this week. It's already released.

The time has come. Huzzah! cACK

[DanGould]

Would this also let us bring payjoin-ffi into the single workspace? That'd be very convenient in that rust-analyzer could give you a single workspace compilation status at any time while developing.

[spacebear21]

Would this also let us bring payjoin-ffi into the single workspace?

I think so, the main blocker was uniffi 0.29 which appears to be on Rust 1.82.

[zealsham]

@benalleng Does this mean i can bump back the toml version in #947 to more recent version if this goes in before that

[benalleng]

yes it should, as long as the more recent versions of toml are under 1.85 (I'm pretty sure they are)

[DanGould]

@benalleng you asked offline but I want to broadcast to all. Let's move on this. PRs that require MSRV 1.85 should now be accepted. I think this issue can be closed when CI and documentation reflect this change.