Pin bcrypt to 4.0.1 for compatibility with passlib

backend/requirements.txt

@@ -2,6 +2,7 @@ fastapi==0.104.1
 uvicorn[standard]==0.24.0
 sqlalchemy==2.0.23
 python-jose[cryptography]==3.3.0
+bcrypt==4.0.1
 passlib[bcrypt]==1.7.4
 python-multipart==0.0.6
 pydantic==2.5.0