Dear Maintainer,

OpenSSH upstream added a new hybrid hostkey type ssh_host_mldsa44_ed25519_key.pub.

It is enabled by default, and can be created with ssh-keygen -A.

The openssh-server postinst script however doesn't use ssh-keygen -A and instead only generates hostkeys of known types and the ones that are configured in the sshd config.

It appears that it currently doesn't know about mldsa44_ed25519 host key type, please add support for this new host key type.


```
Setting up openssh-server (1:10.4p1-2) ...
Creating config file /etc/ssh/sshd_config with new version
Creating SSH2 RSA key; this may take some time ...
3072 SHA256:YnsFWosh7fXafsy54N5Ly8Xhcs2cyN3G7QSqNbOru2o root@7b108694ebc2 (RSA)
Creating SSH2 ECDSA key; this may take some time ...
256 SHA256:Bd/QtLaV17Kb00huRz1wOeDnSgxQDe3XvffKshbAgWg root@7b108694ebc2 (ECDSA)
Creating SSH2 ED25519 key; this may take some time ...
256 SHA256:Nsx0T7zLEBNiYkELwLbX44pkYqG0DMEBalJ+bNB23ss root@7b108694ebc2 (ED25519)
...
# ssh-keygen -A
ssh-keygen: generating new host keys: MLDSA44-ED25519
...
# ls -latr *.pub
-rw-r--r-- 1 root root  571 Jul 28 10:52 ssh_host_rsa_key.pub
-rw-r--r-- 1 root root  179 Jul 28 10:52 ssh_host_ecdsa_key.pub
-rw-r--r-- 1 root root   99 Jul 28 10:52 ssh_host_ed25519_key.pub
-rw-r--r-- 1 root root 1895 Jul 28 10:53 ssh_host_mldsa44_ed25519_key.pub
```

Likely postinst needs to learn about mldsa44_ed25519 type/filename.

The upstream changelog doesn't suggest to me that it's ready to be
enabled yet:

  * All: add experimental support for a composite post-quantum
    signature scheme that combines ML-DSA 44 and Ed25519 as specified
    in draft-miller-sshm-mldsa44-ed25519-composite-sigs.

    This scheme is not enabled by default. To use it, you'll need
    to add it to HostKeyAlgorithms, PubkeyAcceptedAlgorithms, etc.
    Keys may be generated using "ssh-keygen -t mldsa44-ed25519".

Yes, it's enabled by default _specifically in ssh-keygen -A_, but it's
not enabled by default in the rest of OpenSSH, so I think it's too early
at this point.  I'll wait until upstream declares it to be
non-experimental.

Thanks,