CI: Pin cython on 32bit build
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).


Merging to get the CI back to green @mroeschke Can you pin this everywhere? (xref https://github.com/pandas-dev/pandas/pull/47891#pullrequestreview-1054894065). We should probably also report this to Cython. Looks like someone already reported this. The fix is in https://github.com/cython/cython/pull/4929