[TEST][CUDA] Use proper dtype in test_cuda_tensor_pow_scalar_tensor_cuda (pytorch#163070)

The test `test_binary_ufuncs.py::TestBinaryUfuncsCUDA::test_cuda_tensor_pow_scalar_tensor_cuda` fails with a mismatched `dtype`:
```Python
AssertionError: The values for attribute 'dtype' do not match: torch.float32 != torch.float64.
```
This PR forces both arguments to use the same `dtype` to fix the test failure.

Pull Request resolved: pytorch#163070
Approved by: https://github.com/eqy

Author: Aidyn-A

test/test_binary_ufuncs.py

@@ -1480,8 +1480,8 @@ def to_np(value):
                     self.assertRaisesRegex(RuntimeError, regex, base.pow_, exponent)
                 elif torch.can_cast(torch.result_type(base, exponent), base.dtype):
                     actual2 = actual.pow_(exponent)
-                    self.assertEqual(actual, expected)
-                    self.assertEqual(actual2, expected)
+                    self.assertEqual(actual, expected.to(actual))
+                    self.assertEqual(actual2, expected.to(actual2))
                 else:
                     self.assertRaisesRegex(
                         RuntimeError,