BUG: Fix #61222: Keep index name when resampling with pyarrow dtype

Author: mthiboust

pandas/core/resample.py

@@ -517,7 +517,9 @@ def _wrap_result(self, result):
             result.name = getattr(obj, "name", None)
 
         if self._timegrouper._arrow_dtype is not None:
+            obj = self.obj
             result.index = result.index.astype(self._timegrouper._arrow_dtype)
+            result.index.name = getattr(obj.index, "name", None)
 
         return result