Loosen numpy requirement

[veenstrajelmer]

Is your feature request related to a problem? Please describe.
Numpy was set to ^1.26 for py3.12 in #599, but this is the most recent version and last 1-version, the next one is 2.0.0. This seems to be too tight.

Describe the solution you'd like
Loosen the numpy requirement to the oldest supported version, this is 1.24 according to https://endoflife.date/numpy

However, this version does not work, poetry complains: "Note: This error originates from the build backend, and is likely not a problem with poetry but with numpy (1.24.4) not supporting PEP 517 builds. You can verify this by running 'pip wheel --no-cache-dir --use-pep517 "numpy (==1.24.4)"'."