Add CIS Debian 13 SSH KEX and MAC algorithm options

[israel-villar]

• sshd_strong_kex.var: add cis_debian13 option with the CIS Debian 13 approved KEX algorithms. Includes mlkem768x25519-sha256 (ML-KEM / CRYSTALS-Kyber post-quantum algorithm) available in OpenSSH 9.9+ which ships with Debian 13.
• sshd_strong_macs.var: add cis_debian13 option with the CIS Debian 13 approved MAC algorithms (identical to cis_debian12).

Description:

Add cis_debian13 options to the SSH KEX and MAC algorithm variables
for use with the CIS Debian Linux 13 Benchmark v1.0.0.

• sshd_strong_kex.var: adds cis_debian13 with the CIS-approved KEX
  algorithms. Includes mlkem768x25519-sha256, a post-quantum (ML-KEM /
  CRYSTALS-Kyber) algorithm available in OpenSSH 9.9+ which ships with
  Debian 13 (Trixie).
• sshd_strong_macs.var: adds cis_debian13 with the CIS-approved MAC
  algorithms (identical to cis_debian12).

Rationale:

Without these entries the profile cannot set product-specific algorithm
lists via var_sshd_strong_kex=cis_debian13 in the profile selections.
The post-quantum KEX algorithm is explicitly recommended by CIS Debian 13
section 5.1.x given OpenSSH 9.9 availability on Trixie.

Review Hints:

Two one-line additions, one per var file. Mirror the pattern of the
existing cis_debian12 entries immediately above.

[openshift-ci]

Hi @israel-villar. Thanks for your PR.

I'm waiting for a ComplianceAsCode member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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