[feature request] Support for hashing algorithms RFC8760

[kadabusha]

Looking forward to having the support for RFC8760 implemented in sipp to allow usage of different hashing algorithms.

This specification adds new secure algorithms to be used with the
   Digest mechanism to authenticate users.  The obsolete MD5 algorithm
   remains only for backward compatibility with [RFC2617], but its use
   is NOT RECOMMENDED.

List of suggested algorithms, bolded items are currently not supported:

algorithm = "algorithm" EQUAL ( **"MD5" / "MD5-sess" / "SHA-256" / "SHA-256-sess" / "SHA-512-256" / "SHA-512-256-sess" / token )

Re: MD5-sess, I have not found support for that in source code upon grep of files, neither in github in issues. There is one mention 15 years ago in mailing lists that it's not supported: https://sourceforge.net/p/sipp/mailman/message/9012235/