Use iter_swap instead of swap

Author: mika314

chapters/algorithms/bubble_sort/code/c++/bubblesort.cpp

@@ -16,7 +16,7 @@ void bubble_sort(Iter first, Iter last) {
     for (auto it2 = first; it2 + 1 != last; ++it2) {
       // these are unsorted! gotta swap 'em
       if (*(it2 + 1) < *it2) {
-        std::swap(*it2, *(it2 + 1));
+        std::iter_swap(it2, (it2 + 1));
       }
     }
   }