Making uluru optional

Author: Pauan

Cargo.toml

@@ -25,7 +25,7 @@ spans = ["wasm-bindgen-macro/spans"]
 std = []
 serde-serialize = ["serde", "serde_json", "std"]
 nightly = []
-enable-interning = ["std"]
+enable-interning = ["std", "uluru"]
 
 # Whether or not the `#[wasm_bindgen]` macro is strict and generates an error on
 # all unused attributes
@@ -39,7 +39,7 @@ xxx_debug_only_print_generated_code = ["wasm-bindgen-macro/xxx_debug_only_print_
 wasm-bindgen-macro = { path = "crates/macro", version = "=0.2.48" }
 serde = { version = "1.0", optional = true }
 serde_json = { version = "1.0", optional = true }
-uluru = "0.3.0"
+uluru = { version = "0.3.0", optional = true }
 cfg-if = "0.1.9"
 
 [target.'cfg(target_arch = "wasm32")'.dev-dependencies]