Fix/make pep 518 compliant

pyproject.toml

@@ -0,0 +1,2 @@
+[build-system]
+requires = ["cython", "numpy", "setuptools", "wheel"]

setup.py

@@ -1,15 +1,32 @@
-from distutils.core import setup
-from distutils.extension import Extension
-from Cython.Distutils import build_ext
-import numpy
-from Cython.Build import cythonize
+import subprocess
+import sys
 
-setup(
-    name='choldate',
-    version='0.1.0',
-    packages=['choldate','choldate.test'],
-    cmdclass = {'build_ext': build_ext},
-    ext_modules = cythonize([Extension("choldate._choldate", ["choldate/_choldate.pyx"],include_dirs = [numpy.get_include()])
-    ]), requires=['numpy','cython']
+import setuptools  # type: ignore
+from setuptools import Extension, setup
+
+try:
+    from numpy import __version__ as numpy_version
+    from numpy import get_include
+except ImportError:
+    subprocess.check_call([sys.executable, "-m", "pip", "install", "numpy"])
+    from numpy import __version__ as numpy_version
+    from numpy import get_include
+
+try:
+    from Cython.Build import cythonize
+except ImportError:
+    subprocess.check_call([sys.executable, "-m", "pip", "install", "Cython"])
+    from Cython.Build import cythonize  # type: ignore
 
+
+ext_modules = cythonize([Extension("choldate._choldate", ["choldate/_choldate.pyx"], include_dirs=[get_include()])])
+
+setup(
+    name="choldate",
+    version="0.1.0",
+    packages=setuptools.find_packages(),
+    include_package_data=True,
+    ext_modules=ext_modules,
+    install_requires=(base_packages := [f"numpy>={numpy_version}"]),
+    zip_safe=False,
 )