Update pyproject.toml

mkoeppe · wkschwartz · web-flow · commit 399f3a6ebe3b · 2023-02-18T14:43:52.000-08:00
Co-authored-by: William Schwartz &lt;wkschwartz@gmail.com&gt;
diff --git a/pyproject.toml b/pyproject.toml
@@ -1,2 +1,2 @@
 [build-system]
-requires = ['setuptools', 'cython <3']
+requires = ['setuptools', 'cython <3, >=0.21']
