Issue #571: Compatibility with >= Numpy 2.0.0 (update of ptp method)

[Chip2916]

#571

In this PR:

• Replaced use of x.ptp() with np.ptp(x) as per depreciation of x.ptp() as part of migration to Numpy 2.0.0.
• Although not raised in original issue, when running tests noticed that they have also depreciated the use of np.Inf to ensure there is only one way to call the attribute. Therefore have replaced np.Inf with np.inf where it appears in package.

Notes:

• Existing unit tests cover changes

[Chip2916]

This PR is related to issue #571

[hbaniecki]

thanks!