Upgrade to axum 0.8

[ethanhann]

Axum 0.8 no longer uses async_trait:
https://tokio.rs/blog/2025-01-01-announcing-axum-0-8-0#async_trait-removal

[masato-hi]

Maybe the Provider needs a Send.

masato-hi@e922a0d

[ethanhann]

@masato-hi Why do you think Send is needed? I ask because the tests pass without it and I don't see any issues.

[masato-hi]

@ethanhann
MyProvider needs Send because axum's Handler needs Send.
But InjectProvided Generics did not need it.
Forget my comment.

In other words, adding this line will cause an error, but just adding Send to MyProvider solves it.
masato-hi@e922a0d#diff-86b3ddc2eb3140b3300df4d6542a34f809cfe3345bd1a9746cf59eef24f9bbdbR38

[ethanhann]

@AzureMarker Does this look ok to merge to you?

[AzureMarker]

I see axum 0.8 added the Sync requirement:

breaking: Require Sync for all handlers and services added to Router and MethodRouter (tokio-rs/axum#2473)

https://github.com/tokio-rs/axum/blob/main/axum/CHANGELOG.md#080

[AzureMarker]

Thanks for the PR! I'll release the change after merge.

[AzureMarker]

shaku_axum 0.6.0 has been released with axum 0.8 support.