Fix rand 0.10.0 compatibility in ZJIT parcopy tests

rand 0.10.0 moved `random_range` from the `Rng` trait to `RngExt`.
Update the import accordingly.

Author: k0kubun

zjit/src/backend/parcopy.rs

@@ -117,7 +117,7 @@ pub fn sequentialize_register<T: PartialEq + Eq + Hash + Ord + std::fmt::Debug +
 
 #[cfg(test)]
 mod tests {
-    use rand::Rng;
+    use rand::RngExt;
     use std::collections::HashMap;
 
     use super::*;