update axum to v0.8

[Atrox]

No description provided.

[Tumas]

MSRV should also be updated to 1.75. See tokio-rs/axum#2943

[Tumas]

axum::async_trait was removed, See: https://github.com/tokio-rs/axum/releases/tag/axum-core-v0.5.0

Removing #[axum::async_trait] should be enough

[jkauffmann-ubi]

Is there anything we can do to help this getting in and released ? Are there any concerns ?

axum 0.8 has been out for some time now and serde_qs is the only crate that is still keeping us from upgrading.

[JMicheli]

Hey there, I'd also like to support this pull request being merged and a new release out. Currently, this is the only thing blocking stump from upgrading to Axum 0.8.

[samscott89]

Thanks for the help here all! I'd like to keep the rustversion as low as possible for folks who aren't using axum. I'm going to revert that part of the change, and will deal with getting it properly tested in a separate PR.