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/assets/Assets.cpp

@@ -1,7 +1,6 @@
 #include "Assets.hpp"
 
-Assets::~Assets() {
-}
+Assets::~Assets() = default;
 
 const std::vector<TextureAnimation>& Assets::getAnimations() {
     return animations;

src/assets/Assets.hpp

@@ -68,7 +68,7 @@ class Assets {
     std::unordered_map<std::type_index, assets_map> assets;
     std::vector<assetload::setupfunc> setupFuncs;
 public:
-    Assets() {}
+    Assets() = default;
     Assets(const Assets&) = delete;
     ~Assets();