security/py-ssh-audit: update to 2.3.1

Changelog:

• Now parses public key sizes for rsa-sha2-256-cert-v01@openssh.com and rsa-sha2-512-cert-v01@openssh.com host key types.
• Flag ssh-rsa-cert-v01@openssh.com as a failure due to SHA-1 hash.
• Fixed bug in recommendation output which suppressed some algorithms inappropriately.
• Built-in policies now include CA key requirements (if certificates are in use).
• Lookup function (--lookup) now performs case-insensitive lookups of similar algorithms; credit Adam Russell.
• Migrated pre-made policies from external files to internal database.
• Split single 3,500 line script into many files (by class).
• Added setup.py support; credit Ganden Schaffner.
• Added 1 new cipher: des-cbc@ssh.com.