Update code to resolve DeprecationWarning

[chriscarrollsmith]

================================================================================== warnings summary =================================================================================== 
tests/test_data.py::test_imf_dataset_params_list_request
tests/test_data.py::test_imf_dataset_params_list_request
  C:\Users\chris\Software\Python\imfp\.venv\Lib\site-packages\pandas\core\algorithms.py:522: DeprecationWarning: np.find_common_type is deprecated.  Please use `np.result_type` or `np.promote_types`.
  See https://numpy.org/devdocs/release/1.25.0-notes.html and the docs for more information.  (Deprecated NumPy 1.25)
    common = np.find_common_type([values.dtype, comps_array.dtype], [])

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html