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/content/ContentPack.cpp

@@ -142,5 +142,4 @@ ContentPackRuntime::ContentPackRuntime(
 {
 }
 
-ContentPackRuntime::~ContentPackRuntime() {
-}
+ContentPackRuntime::~ContentPackRuntime() = default;