Removed remove() operation from FilteredIterator

FilteredIterator can not support remove() operation at the current time in a correct way since it needs to look ahead on the underlying iterator.

src/main/java/org/cactoos/list/FilteredIterator.java

@@ -108,7 +108,9 @@ public X next() {
 
     @Override
     public void remove() {
-        this.iterator.remove();
+        throw new UnsupportedOperationException(
+            "FilteredIterator does not support remove Operation"
+        );
     }
 
 }