Clean up iterator in generic for loop

src/Evaluator/Evaluator.cpp

@@ -174,6 +174,7 @@ namespace Porygon::Evaluation {
             }
             this -> EvaluateBlockStatement(block);
         }
+        delete iterator;
     }
 
     /////////////////

src/Evaluator/Iterator/Iterator.hpp

@@ -13,6 +13,7 @@ namespace Porygon::Evaluation{
         virtual shared_ptr<EvalValue> GetCurrent() = 0;
         virtual bool MoveNext() = 0;
         virtual void Reset() = 0;
+        virtual ~Iterator(){}
     };
 
 }