test: use cython==3.0.0a11 to build in CI

Author: oscarbenjamin

.github/workflows/buildwheel.yml

@@ -43,7 +43,7 @@ jobs:
           CIBW_BEFORE_ALL_MACOS: bin/cibw_before_all_macosx_x86_64.sh
           CIBW_BEFORE_ALL_WINDOWS: msys2 -c bin/cibw_before_all_windows.sh
           CIBW_BEFORE_BUILD_WINDOWS: msys2 -c bin/cibw_before_build_windows.sh
-          CIBW_BEFORE_BUILD: pip install numpy cython delvewheel
+          CIBW_BEFORE_BUILD: pip install numpy cython==3.0.0a11 delvewheel
           CIBW_ENVIRONMENT: >
             C_INCLUDE_PATH=$(pwd)/.local/include/
             LIBRARY_PATH=$(pwd)/.local/lib/