[BUG] cudf.pivot doesn't understand "values"

[KazukiOnodera]

Describe the bug
cudf.pivot doesn't understand "values" when it's column name instead of list and the column name includes numeric

Steps/Code to reproduce bug

import cudf
df = cudf.DataFrame([
    ['A', 'a', 0, 0, 0],
    ['A', 'b', 1, 1, 1],
    ['A', 'c', 2, 2, 2],
    ['B', 'a', 0, 0, 0],
    ['B', 'b', 1, 1, 1],
    ['B', 'c', 2, 2, 2],
    ['C', 'a', 0, 0, 0],
    ['C', 'b', 1, 1, 1],
    ['C', 'c', 2, 2, 2],
], columns=['x', 'y', 'z', 'z123', '123z'])

This works
cudf.pivot(df, index='x', columns='y', values='z')

This doesn't work
cudf.pivot(df, index='x', columns='y', values='z123')

KeyError Traceback (most recent call last)
Input In [18], in
----> 1 cudf.pivot(df, index="x", columns="y", values="z123")

File ~/anaconda3/envs/rapids-22.02/lib/python3.8/site-packages/cudf/core/reshape.py:924, in pivot(data, index, columns, values)
920 values = df._columns_view(
921 col for col in df._column_names if col not in (index, columns)
922 )
923 else:
--> 924 values = df._columns_view(values)
925 if index is None:
926 index = df.index

File ~/anaconda3/envs/rapids-22.02/lib/python3.8/site-packages/cudf/core/dataframe.py:5580, in DataFrame._columns_view(self, columns)
5575 def _columns_view(self, columns):
5576 """
5577 Return a subset of the DataFrame's columns as a view.
5578 """
5579 return DataFrame(
-> 5580 {col: self._data[col] for col in columns}, index=self.index
5581 )

File ~/anaconda3/envs/rapids-22.02/lib/python3.8/site-packages/cudf/core/dataframe.py:5580, in (.0)
5575 def _columns_view(self, columns):
5576 """
5577 Return a subset of the DataFrame's columns as a view.
5578 """
5579 return DataFrame(
-> 5580 {col: self._data[col] for col in columns}, index=self.index
5581 )

File ~/anaconda3/envs/rapids-22.02/lib/python3.8/site-packages/cudf/core/column_accessor.py:156, in ColumnAccessor.getitem(self, key)
155 def getitem(self, key: Any) -> ColumnBase:
--> 156 return self._data[key]

KeyError: '1'

This works
cudf.pivot(df, index='x', columns='y', values=['z123'])

This works
cudf.pivot(df, index='x', columns='y', values=['z', 'z123', '123z'])

Environment overview
cudf version is "22.02.00"

[shaswat-indian]

I'm taking this up.