factor: expand glob import in test

tests/by-util/test_factor.rs

@@ -118,7 +118,7 @@ fn test_cli_args() {
 
 #[test]
 fn test_random() {
-    use conv::prelude::*;
+    use conv::prelude::ValueFrom;
 
     let log_num_primes = f64::value_from(NUM_PRIMES).unwrap().log2().ceil();
     let primes = Sieve::primes().take(NUM_PRIMES).collect::<Vec<u64>>();