Update dependencies in requirements.txt

Split passlib and bcrypt into separate entries for clarity and maintainability. Ensured all other dependencies remain unchanged to avoid potential compatibility issues.

backend/requirements.txt

@@ -2,5 +2,7 @@ fastapi==0.115.0
 uvicorn[standard]==0.30.6
 SQLAlchemy==2.0.34
 psycopg[binary]==3.2.2
-passlib[bcrypt]==1.7.4
 python-multipart==0.0.9
+
+passlib==1.7.4
+bcrypt==3.2.2