Support numpy 2.0

Per numpy's instructions, build with numpy >= 1.25 and test with numpy
1.19.

.github/requirements-oldest-numpy.txt

@@ -0,0 +1,5 @@
+pytest==8.2.1
+numpy==1.19.3; python_version=='3.9'
+numpy==1.21.6; python_version=='3.10'
+numpy==1.23.2; python_version=='3.11'
+numpy==1.26.2; python_version=='3.12'

.github/workflows/build_wheels.yaml

@@ -39,7 +39,7 @@ jobs:
           version: 13
           arch: 'x86_64'
 
-        python: ['cp38', 'cp39', 'cp310', 'cp311', 'cp312']
+        python: ['cp39', 'cp310', 'cp311', 'cp312']
 
     steps:
       - uses: actions/[email protected]

pyproject.toml

@@ -17,7 +17,7 @@ classifiers=[
     "License :: OSI Approved :: BSD License",
     "Topic :: Scientific/Engineering :: Physics",
     ]
-dependencies = ["numpy>=1.9.3"]
+dependencies = ["numpy>=1.19.0"]
 
 [project.scripts]
 gsd = "gsd.__main__:main"
@@ -36,12 +36,12 @@ packages = ["gsd", "gsd.test"]
 requires = ["setuptools>=64.0.0",
             "wheel",
             "Cython",
-            "oldest-supported-numpy"]
+            "numpy>=2.0.0rc1"]
 
 [tool.cibuildwheel]
 # Test the wheels.
 test-command = "pytest --pyargs gsd -v --log-level=DEBUG"
-test-requires = "pytest"
+before-test = "python3 -m pip install -r .github/requirements-oldest-numpy.txt --no-binary :all: --force-reinstall"
 
 # Build on 64-bit architectures.
 archs = ["auto64"]