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/graphics/render/Skybox.cpp

@@ -55,8 +55,7 @@ Skybox::Skybox(uint size, Shader* shader)
     });
 }
 
-Skybox::~Skybox() {
-}
+Skybox::~Skybox() = default;
 
 void Skybox::drawBackground(Camera* camera, Assets* assets, int width, int height) {
     auto backShader = assets->get<Shader>("background");