Remove broken dead SetManager.__next__ method

SetManager.__iter__ returns iter(self.elements), so the for-loop
protocol never calls __next__ on the SetManager itself. The method
also had two concrete bugs: self.count was never initialized and
self.elements (a set) is not subscriptable. No callers exist.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: derek73

nameparser/config/__init__.py

@@ -73,15 +73,6 @@ def __contains__(self, value):
     def __len__(self):
         return len(self.elements)
 
-    def __next__(self):
-        if self.count >= len(self.elements):
-            self.count = 0
-            raise StopIteration
-        else:
-            c = self.count
-            self.count = c + 1
-            return getattr(self, self.elements[c]) or next(self)
-
     def add_with_encoding(self, s, encoding=None):
         """
         Add the lower case and no-period version of the string to the set. Pass an