Fix typo in exception raised when attempting to convert a string colu…

…mn to cupy (#17800)

Closes #17799

Fix typo in exception raised when attempting to convert a string column to cupy

Authors:
  - David Gardner (https://github.com/dagardner-nv)
  - GALI PREM SAGAR (https://github.com/galipremsagar)
  - Matthew Roeschke (https://github.com/mroeschke)
  - Bradley Dice (https://github.com/bdice)
  - Vyas Ramasubramani (https://github.com/vyasr)

Approvers:
  - Matthew Roeschke (https://github.com/mroeschke)
  - GALI PREM SAGAR (https://github.com/galipremsagar)

URL: #17800

python/cudf/cudf/core/column/string.py

@@ -5929,7 +5929,7 @@ def values(self) -> cupy.ndarray:
         """
         Return a CuPy representation of the StringColumn.
         """
-        raise TypeError("String Arrays is not yet implemented in cudf")
+        raise TypeError("String arrays are not supported by cupy")
 
     def to_pandas(
         self,