BLD: update cython to 0.29.21

1 files changed, 2 insertions, 2 deletions

diff --git a/tools/cythonize.py b/tools/cythonize.py
index 65b79f716..6cebf0f72 100755
--- a/tools/cythonize.py
+++ b/tools/cythonize.py
@@ -66,11 +66,11 @@ def process_pyx(fromfile, tofile):
         # check the version, and invoke through python
         from distutils.version import LooseVersion
 
-        # Cython 0.29.14 is required for Python 3.8 and there are
+        # Cython 0.29.21 is required for Python 3.9 and there are
         # other fixes in the 0.29 series that are needed even for earlier
         # Python versions.
         # Note: keep in sync with that in pyproject.toml
-        required_version = LooseVersion('0.29.14')
+        required_version = LooseVersion('0.29.21')
 
         if LooseVersion(cython_version) < required_version:
             raise RuntimeError(f'Building {VENDOR} requires Cython >= {required_version}')