Revert "Add return_void to Task"

This reverts commit 79677d12.

rt/include/typon/task.hpp

@@ -138,14 +138,7 @@ namespace typon
       _coroutine.promise()._continuation = std::noop_coroutine();
       _coroutine.resume();
     }
-
-    void return_void() noexcept = delete;
   };
-
-  template <>
-  void Task<void>::return_void() noexcept
-  {
-  }
   
 }