Fix Botan's "warning: 'Kyber1024' is deprecated"

[ni4]

Description

The following warning is issued if PQC support is enabled:

warning: 'Kyber1024' is deprecated: Use Kyber1024_R3 [-Wdeprecated-declarations]
    Botan::KyberMode result = Botan::KyberMode::Kyber1024;

[ni4]

cc @falko-strenzke @TJ-91

[falko-strenzke]

OK, we will take care, hopefully in the next week.

[TJ-91]

Botan renamed the enum values and deprecated the old ones. Botan 3.0 up to 3.1.1 only know the old values, 3.2.0 and upwards know the new values and the deprecated old values. I will make a PR to fix this for the time being. We won't need the fix any more when Botan releases the final ML-KEM implementation and we switch to that.

Also note that Botan 3.2.0 (and probably some versions below, I did not check) will emit a lot of warnings about deprecated Kyber 90s. However, this is a problem in the Botan Header and I cannot really do anything here. Newer versions are fine.

[ni4]

Quick look at https://pkgs.org/search/?q=Botan shows that most systems use Botan 2.x, and ones which use 3.x are already 3.2+. So probably it would be easier solution to require Botan 3.2.+ if PQC is enabled, I doubt that somebody would stick to 3.1.

[TJ-91]

That's easier, yes. I changed it to require Botan 3.2