fix: accidentally inverted condition

Author: haggholm

lib/dereference.js

@@ -141,7 +141,7 @@ function dereference$Ref ($ref, path, pathFromRoot, parents, processedObjects, d
 
   // Check for circular references
   let directCircular = pointer.circular;
-  let circular = directCircular || !parents.has(pointer.value);
+  let circular = directCircular || parents.has(pointer.value);
   circular && foundCircularReference(path, $refs, options);
 
   // Dereference the JSON reference