[BUG] nsmallest & nlargest are not raising an error for string dtype

[galipremsagar]

Describe the bug
nsmallest & nlargest shouldn't be returning results when string columns are present, but cudf is currently returning a result.

Steps/Code to reproduce bug

In [1]: import cudf
s = 
In [2]: s = cudf.Series(['a', 'b', 'c', 'd'])
s.
In [3]: s.nlargest(1)
Out[3]: 
3    d
dtype: object

In [4]: s.to_pandas().nlargest(1)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[4], line 1
----> 1 s.to_pandas().nlargest(1)

File /nvme/0/pgali/envs/cudfdev/lib/python3.10/site-packages/pandas/core/series.py:4134, in Series.nlargest(self, n, keep)
   4036 def nlargest(
   4037     self, n: int = 5, keep: Literal["first", "last", "all"] = "first"
   4038 ) -> Series:
   4039     """
   4040     Return the largest `n` elements.
   4041 
   (...)
   4132     dtype: int64
   4133     """
-> 4134     return algorithms.SelectNSeries(self, n=n, keep=keep).nlargest()

File /nvme/0/pgali/envs/cudfdev/lib/python3.10/site-packages/pandas/core/algorithms.py:1277, in SelectN.nlargest(self)
   1275 @final
   1276 def nlargest(self):
-> 1277     return self.compute("nlargest")

File /nvme/0/pgali/envs/cudfdev/lib/python3.10/site-packages/pandas/core/algorithms.py:1317, in SelectNSeries.compute(self, method)
   1315 dtype = self.obj.dtype
   1316 if not self.is_valid_dtype_n_method(dtype):
-> 1317     raise TypeError(f"Cannot use method '{method}' with dtype {dtype}")
   1319 if n <= 0:
   1320     return self.obj[[]]

TypeError: Cannot use method 'nlargest' with dtype object

Expected behavior
Raise an error similar to pandas.

Environment overview (please complete the following information)

• Environment location: [Bare-metal]
• Method of cuDF install: [from source]