Fixes TimezoneInfo.utcoffset() method

Author: sdispater

pendulum/tz/timezone_info.py

@@ -51,7 +51,7 @@ def utcoffset(self, dt):
         elif dt.tzinfo is not self:
             dt = self.tz.convert(dt)
 
-            return dt.tzinfo._adjusted_offset
+            return dt.tzinfo._transition_type.adjusted_offset
         else:
             return self._transition_type.adjusted_offset