Remove trailing whitespace

Removed trailing whitespace which caused to fail pretty-check

src/liballoc/vec.rs

@@ -1472,7 +1472,7 @@ impl<T: Clone> Vec<T> {
     /// difference, with each additional slot filled with `value`.
     /// If `new_len` is less than `len`, the `Vec` is simply truncated.
     ///
-    /// This method requires `T` to implement [`Clone`], 
+    /// This method requires `T` to implement [`Clone`],
     /// in order to be able to clone the passed value.
     /// If you need more flexibility (or want to rely on [`Default`] instead of
     /// [`Clone`]), use [`resize_with`].