Relax the build dependency on NumPy

Do not pin NumPy build dependencies to specific versions.  It is
no longer necessary since NumPy 1.25, as it automatically exposes
"an API that is backwards compatible with the oldest NumPy version that
supports the currently oldest compatible Python version" -- effectively
removing the need to maintain downstream compatibility matrices.

See: https://numpy.org/devdocs/dev/depending_on_numpy.html#adding-a-dependency-on-numpy

Author: mgorny

pyproject.toml

@@ -1,8 +1,9 @@
 [build-system]
 requires = [
   "numpy<2.0; python_version<'3.9'",
-  "numpy==2.0.2; python_version>='3.9' and python_version<'3.13'",
-  "numpy==2.1.3; python_version=='3.13'",
+  # NumPy >=1.25 defaults to exposing "an API that is backwards compatible with the oldest NumPy version that supports the currently oldest compatible Python version"
+  # https://numpy.org/devdocs/dev/depending_on_numpy.html#adding-a-dependency-on-numpy
+  "numpy>=2.0; python_version>='3.9'",
   "packaging",
   "pip",
   "scikit-build>=0.14.0",