The argon2 module has produced hashes, that where not conforming with 
the specification and thus it was not compatible with other argon2
implementations.

This has been fixed and to avoid accidentally compiling projects with 
the buggy argon2 module, the API has been slightly changed:

  * renamed argon2::config to argon2::conf
  * renamed argon2::default_config to argon2::default_conf
  * renamed argon2::low_mem_config to argon2::low_mem_conf

If you are using argon2 or the crypto::derivekey function, you will
have to migrate your hashes. One way would be to vendor the buggy argon2
module at commit 11db66bdb7574ee8f6d642dea0498907f9121b6b to support the
current hashes and provide the user tools to rehash. See the latest 
commits at the himitsu project for ideas:

https://git.sr.ht/~sircmpwn/himitsu