Add `numpy<2.0` to requirements

[ortk95]

The NumPy API may change in 2.0 (https://github.com/numpy/numpy/issues/24300), so ensure we are only using NumPy 1.x until we have properly tested NumPy 2.0.

Pull request checklist

• [x] Add a clear description of the change
• [ ] Add any new tests needed
• [ ] Run spell check on new text visible to user (documentation, GUI etc.)
• [x] Check any changes to requirements.txt are reflected in setup.py
• [ ] Check code passes CI checks (run run_ci.sh or check GitHub Actions)

See CONTRIBUTING.md for more details.

[coveralls]

Pull Request Test Coverage Report for Build 6531921916

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 99.5%

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Totals
Change from base Build 6480625521:	0.0%
Covered Lines:	2759
Relevant Lines:	2773

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💛 - Coveralls