Replace passlib with bcrypt

[LilDojd]

Summary:

This pull request replaces the usage of the passlib library with bcrypt for password hashing and verification.

Changes:

• remove passlib from conda environments and auth.py
• Added BcryptPasswordHandler with same defaults as in passlib.context.CryptContext

See #304 for motivation

[pep8speaks]

Hello @LilDojd! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file alchemiscale/security/auth.py:

Line 37:63: E203 whitespace before ':'
Line 41:80: E501 line too long (82 > 79 characters)
Line 72:80: E501 line too long (83 > 79 characters)