Add to_public_user test

tests/user.rs

@@ -0,0 +1,18 @@
+use chorus::types::{PublicUser, Snowflake, User};
+
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
+#[cfg_attr(not(target_arch = "wasm32"), test)]
+fn to_public_user() {
+    let mut user = User::default();
+    let mut public_user = PublicUser {
+        username: Some("".to_string()),
+        discriminator: Some("".to_string()),
+        ..Default::default()
+    };
+    let id: Snowflake = 1_u64.into();
+    user.id = id;
+    public_user.id = id;
+
+    let from_user = user.into_public_user();
+    assert_eq!(public_user, from_user);
+}