mypy fixup

Author: jbrockmendel

pandas/core/resample.py

@@ -1192,8 +1192,7 @@ def _gotitem(self, key, ndim, subset=None):
         """
         # create a new object to prevent aliasing
         if subset is None:
-            # error: "GotItemMixin" has no attribute "obj"
-            subset = self.obj  # type: ignore[attr-defined]
+            subset = self.obj
 
         # we need to make a shallow copy of ourselves
         # with the same groupby