Fix unused import error.

BurntSushi · BurntSushi · commit c4f065506193 · 2016-05-18T09:30:49.000-04:00
diff --git a/regex-syntax/src/properties.rs b/regex-syntax/src/properties.rs
@@ -9,7 +9,6 @@
 // except according to those terms.
 
 use quickcheck::{Arbitrary, Gen, Testable, QuickCheck, StdGen};
-use rand::Rng;
 
 use {
     Expr, ExprBuilder,
