Update to Argon2

[jmoreira-valory]

Proposed changes

Update password hash to Argon2, winner of the Password Hashing Competition.

• Upon successful login, the middleware will update the current hash format to Argon2.
• If login is unsuccessful, it will not modify the hash value.

⚠️ Breaking change!!!
Once the .operate folder is loaded with this version of the middleware, the folder will no longer work with older versions. (The recommendation is to backup the . operate folder if the user intends to use it with older versions.)

Types of changes

What types of changes does your code introduce?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

[jmoreira-valory]

PT = Pytest style. Suggestion to include it in tomte repository.