Change test_rng import to ark-std

mnt6_298/src/fields/tests.rs

@@ -1,7 +1,8 @@
 use ark_ff::{
     fields::{models::fp6_2over3::*, quadratic_extension::QuadExtParameters},
-    test_rng, Field,
+    Field,
 };
+use ark_std::test_rng;
 use rand::Rng;
 
 use crate::*;