build(deps): bump alkcall to 0.8.1

Picks up the duplicate adopt/open collision fix found by alkcall's
manager_routing fuzz campaign (alkcall CHANGELOG 0.8.1): a duplicate
adopt_channel/open_channel no longer replaces the live channel's
state. alkhttp reaches the fixed paths via the shared ChannelManager;
no alkcall API surface used by this crate changed.

Verified: cargo test (456 passed), cargo test --all-features,
clippy --all-targets -- -D warnings, fmt --check.

Cargo.toml

@@ -42,7 +42,7 @@ h2 = ["server", "dep:hyper", "hyper-util/http2", "hyper/http2"]
 http1 = ["server", "dep:hyper", "hyper-util/http1", "hyper/http1"]
 
 [dependencies]
-alkcall = { version = "0.8", features = ["gateway"] }
+alkcall = { version = "0.8.1", features = ["gateway"] }
 arc-swap = { version = "1", optional = true }
 axum = { version = "0.8", optional = true, features = ["ws"] }
 bytes = "1"