lang/python313: fix blake2s_impl regen mismatch

The only difference between "stock" and regenerated blake2s_impl.c
is where a variable is declared in py_blake2s_new_impl(). Patch the
stock file to the regenerated version so the regeneration script
does not get called.

Reported by: fluffy, jan[at]glaubitz[dot]org
PR: 274671