Revert "Try updating cython"

This reverts commit c1b794a.

Author: honnibal

setup.cfg

@@ -35,7 +35,7 @@ python_requires = >=3.7
 # NOTE: This section is superseded by pyproject.toml and will be removed in
 # spaCy v4
 setup_requires =
-    cython>=3.0.0
+    cython>=0.25,<3.0
     numpy>=1.15.0; python_version < "3.9"
     numpy>=1.19.0; python_version >= "3.9"
     # We also need our Cython packages here to compile against