Runtime feature detection fails for ML-DSA on Aarch64

> Thanks a lot for your support! With fix #81 I can compile the code now on my RasPi 4B. ML-DSA-44 quits now with "Illegal instruction". I assume this is because the used ARM Cortex does not support SHA-3, right? 

 _Originally posted by @hfunke in [#77](https://github.com/rustpq/pqcrypto/issues/77#issuecomment-2693844791)_