add missing wasm import

Author: KodrAus

src/timestamp.rs

@@ -447,6 +447,13 @@ pub mod context {
 mod tests {
     use super::*;
 
+    #[cfg(all(
+        target_arch = "wasm32",
+        target_vendor = "unknown",
+        target_os = "unknown"
+    ))]
+    use wasm_bindgen_test::*;
+
     #[test]
     #[cfg_attr(
         all(