fix: optimization: PVS-Studio warning V832

It's better to use '= default;' syntax instead of empty constructor and destructor body.
Using '= default;' can help the compiler generate more optimal code.

Reported by: PVS-Studio

Signed-off-by: Vyacheslav Ivanov <islavaivanov76@gmail.com>

src/util/ThreadPool.hpp

@@ -28,8 +28,8 @@ struct ThreadPoolResult {
 template<class T, class R>
 class Worker {
 public:
-    Worker() {}
-    virtual ~Worker() {}
+    Worker() = default;
+    virtual ~Worker() = default;
     virtual R operator()(const std::shared_ptr<T>&) = 0;
 };