Update accessor.py

Author: bang128

pandas/core/strings/accessor.py

@@ -569,9 +569,7 @@ def cat(
 
         # concatenate Series/Index with itself if no "others"
         if others is None:
-            # error: Incompatible types in assignment (expression has type
-            # "ndarray", variable has type "Series")
-            data = ensure_object(data)  # type: ignore[assignment]
+            data = Series(ensure_object(data))
             na_mask = isna(data)
             if na_rep is None and na_mask.any():
                 return sep.join(data[~na_mask])