ionex: migrate from interp2d to RegularGridInterpolator

[yunjunz]

Description of proposed changes

• objects.ionex.get_ionex_value(): migrate from scipy.interpolate.interp2d() to scipy.interpolate.RegularGridInterpolator(), as the former has been removed since scipy-1.14.

• tests.objects.ionex.py: more print out msg

Reminders

• Pass Pre-commit check (green)
• Pass Codacy code review (green)
• Pass Circle CI unit test (the circleci integration test is failing due to the known gdal issue Cannot import gdal in circle CI testing #1220)
• Pass local integration test
• Make sure that your code follows our style. Use the other functions/files as a basis.
• If modifying functionality, describe changes to function behavior and arguments in a comment below the function declaration.