fix: set `AuthAltTypes="auth/jwt" for jwt authentication

This enables using `slurmrestd` to comunicate with `slurmdbd`.

src/charm.py

@@ -247,6 +247,7 @@ def _write_config_and_restart_slurmdbd(
             }
 
             if self._slurmctld.is_joined:
+                slurmdbd_full_config["AuthAltTypes"] = "auth/jwt"
                 slurmdbd_full_config["AuthAltParameters"] = (
                     '"jwt_key=/var/spool/slurmdbd/jwt_hs256.key"'
                 )