Numpy 2.0 compatibility

[kandersolar]

• [ ] Closes #xxx
• Added tests to cover all new or modified code.
• [ ] Clearly documented all new API functions with PEP257 and numpydoc compliant docstrings.
• [ ] Added new API functions to docs/api.rst.
• [ ] Non-API functions clearly documented with docstrings or comments as necessary.
• Adds description and name entries in the appropriate "what's new" file
  in docs/whatsnew
  for all changes. Includes link to the GitHub Issue with :issue:`num`
  or this Pull Request with :pull:`num`. Includes contributor name
  and/or GitHub username (link with :ghuser:`user`).
• Pull request is nearly complete and ready for detailed review.
• Maintainer: Appropriate GitHub Labels and Milestone are assigned to the Pull Request and linked Issue.

This PR adds compatibility for numpy 2.0, requiring minor changes (just NaN and Inf capitalization) to both the code base and the test suite.

[cwhanse]

thanks @kandersolar