Replace python-jose with PyJWT and update its usage.

Switched the dependency from `python-jose` to `PyJWT` to handle JWT encoding and decoding. Updated related code to use `PyJWT`'s `InvalidTokenError` instead of `JWTError`. Also bumped the application version from `0.1.7` to `0.1.8`.

backend/app/core/security.py

@@ -1,5 +1,5 @@
 from datetime import datetime, timedelta, timezone
-from jose import jwt
+import jwt
 from passlib.context import CryptContext
 from app.core.config import get_settings