Give DamageLibrary an implementation for its destructor.

src/Battling/Library/DamageLibrary.hpp

@@ -7,7 +7,7 @@
 namespace CreatureLib::Battling{
     class DamageLibrary {
     public:
-        virtual ~DamageLibrary();
+        virtual ~DamageLibrary() = default;
         virtual int GetDamage(ExecutingAttack* attack, Creature* target, uint8_t hitIndex) const;
 
         virtual int GetBasePower(ExecutingAttack* attack, Creature* target, uint8_t hitIndex) const;