pytouhou: migrate to `python@3.10`
pytouhou: migrate to `python@3.10`

Also:
- use our `libcython` instead of vendoring it.
- explicitly specify `python3.10` for #107517.

stgraber/homebrew-core,lemzwerg/homebrew-core,adam-moss/homebrew-core,chrisfinazzo/homebrew-core,nbari/homebrew-core,makigumo/homebrew-core,makigumo/homebrew-core,nandub/homebrew-core,Homebrew/homebrew-core,filcab/homebrew-core,stgraber/homebrew-core,nandub/homebrew-core,nbari/homebrew-core,sjackman/homebrew-core,lemzwerg/homebrew-core,sjackman/homebrew-core,filcab/homebrew-core,adam-moss/homebrew-core,Homebrew/homebrew-core,chrisfinazzo/homebrew-core