[WIP] Support Numpy 2

[aaronreidsmith]

Description

Numpy 2 (released 2024-06-16) is binary-incompatible with Numpy 1. This PR aims to make pmdarima compatible with Numpy 2

Fixes #577

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.
Provide instructions so we can reproduce. Please also list any relevant details
for your test configuration

• Test A
• Test B

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes