Enabling the rkyv feature is failing to compile

[tuzz]

Describe the bug When I add features = ["rkyv"] to the leptos dependency, I get an error.

Leptos Dependencies

leptos = { version = "0.6", features = ["rkyv"] }
leptos_axum = { version = "0.6", optional = true }
leptos_meta = { version = "0.6" }
leptos_router = { version = "0.6" }

To Reproduce Steps to reproduce the behavior:

1. cargo leptos new --git leptos-rs/start-axum --name foo
2. cd foo
3. Add features = ["rkyv"] to leptos in Cargo.toml
4. cargo leptos serve

Expected behavior The app compiles successfully.

Screenshots