replace async-std with async-io

[VitalyAnkh]

Objective

• Fixes example async_compute.rs uses the discontinued async-std #19055

Solution

• Replace async-std with async-io.

Testing

CI

[VitalyAnkh]

I’d prefer to list async-io as a direct dependency of this example rather than of Bevy itself. Although Bevy adds async-std as dev-dependency, it appears to be used only here. What do you think?

[alice-i-cecile]

I'm okay with that but I had no idea that was possible. Can you make the change to demonstrate?

[VitalyAnkh]

The plan is to package the async‑compute examples like the mobile example then we could specify dependencies in Cargo.toml (

bevy/examples/mobile/android_basic/Cargo.toml

Line 14 in 0b48587

[dependencies]

), but since dev-dependencies don’t affect runtime, the current arrangement works fine.

This should be ready for merging now.