scheduler: swap based move assignment operator

src/entt/process/scheduler.hpp

@@ -145,7 +145,7 @@ public:
      */
     basic_scheduler &operator=(basic_scheduler &&other) noexcept {
         ENTT_ASSERT(alloc_traits::is_always_equal::value || get_allocator() == other.get_allocator(), "Copying a scheduler is not allowed");
-        handlers = std::move(other.handlers);
+        swap(other);
         return *this;
     }