chore(deps): bump alktype 0.3.0 to 0.4.0

Skeleton revalidated: cargo test, clippy -D warnings, fmt, and the
wasm32-unknown-unknown release build all pass on 0.4.0.

Cargo.toml

@@ -18,7 +18,7 @@ name = "alkgen"
 default = []
 
 [dependencies]
-alktype = "0.3.0"
+alktype = "0.4.0"
 handlebars = "6.4"
 serde = { version = "1", features = ["derive"] }
 serde_json = { version = "1", features = ["preserve_order"] }