Install the argon2-cffi library.
This can be done by running:
python -m pip install django[argon2],
OR
python -m pip install argon2-cffi
PASSWORD_HASHERS = [
'django.contrib.auth.hashers.Argon2PasswordHasher',
'django.contrib.auth.hashers.PBKDF2PasswordHasher',
'django.contrib.auth.hashers.PBKDF2SHA1PasswordHasher',
'django.contrib.auth.hashers.BCryptSHA256PasswordHasher',
'django.contrib.auth.hashers.ScryptPasswordHasher',
]