Use argon2 instead of bcrypt for password hashing

[dantetemplar]

Maybe better to use argon2 instead of bcrypt:
https://github.com/hynek/argon2-cffi

Originally posted by @dantetemplar in #63 (comment)

[dantetemplar]

Suggest to remove passlib at all, they have frequent CVEs (however, it may be a "survivor's mistake" - a lot of attention to passlib, so vulnerabilities are found). Also noisy warnings were from bcrypt so I excluded it from logging.