Wrong version of .NET Core in one of the projects

Books.ConsoleApp/IEnumerableAndIEnumerator.cs

@@ -0,0 +1,18 @@
+namespace Books.Examples
+{
+
+    public interface IEnumerable<out T>
+    {
+        IEnumerator<T> GetEnumerator();
+    }
+    
+    public interface IEnumerator<out T>
+    {
+        T Current { get; }
+
+        bool MoveNext();
+
+        void Reset();
+    }
+    
+}