[MRG] Added numpy bound to the requirements file

[fnhirwa]

Description

This PR adds the numpy bounds for the case where numpy 2 isn't supported yet and added the version to __init__ file for local development, and this will require to bump a version into the __init__ file at every release.

Fixes #579

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation change

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

• Installed pmdarima from this branch and got the numpy version that is lower than numpy 2
• 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