Fix test

Author: YuhanLiin

src/indexmap.rs

@@ -1883,7 +1883,7 @@ mod tests {
     #[test]
     fn partial_eq_floats() {
         // Make sure PartialEq is implemented even if V doesn't implement Eq
-        let map: IndexMap<usize, f32> = Default::default();
+        let map: FnvIndexMap<usize, f32, 4> = Default::default();
         assert_eq!(map, map);
     }
 }