Index: pyproject.toml
--- pyproject.toml.orig
+++ pyproject.toml
@@ -43,7 +43,7 @@ test = [
     'pycodestyle~=2.9.0',
     'pyOpenSSL~=23.0.0',
     'mypy>=0.800',
-    'Cython(>=0.29.36,<0.30.0)',
+    'Cython>=0.29.36',
 ]
 docs = [
     'Sphinx~=4.1.2',
@@ -55,7 +55,7 @@ docs = [
 requires = [
     "setuptools>=60",
     "wheel",
-    "Cython(>=0.29.36,<0.30.0)",
+    "Cython>=0.29.36",
 ]
 build-backend = "setuptools.build_meta"
 
