change self._mgr.dtype to self.dtype

Co-authored-by: Matthew Roeschke <[email protected]>

Author: KevsterAmp

pandas/core/series.py

@@ -2814,7 +2814,7 @@ def round(self, decimals: int = 0, *args, **kwargs) -> Series:
         dtype: float64
         """
         nv.validate_round(args, kwargs)
-        if self._mgr.dtype == "object":
+        if self.dtype == "object":
             raise TypeError("Expected numeric dtype, got object instead.")
         new_mgr = self._mgr.round(decimals=decimals, using_cow=using_copy_on_write())
         return self._constructor_from_mgr(new_mgr, axes=new_mgr.axes).__finalize__(