fix mypy error

jax/_src/pjit.py

@@ -1568,21 +1568,21 @@ def _resolve_in_shardings(args, pjit_in_shardings: Sequence[PjitSharding]
             'Please see the jax.Array migration guide for more information '
             'https://jax.readthedocs.io/en/latest/jax_array_migration.html#handling-of-host-local-inputs-to-pjit-like-batch-etc. '
             f'Got arg shape: {arg.shape}, arg value: {arg}')
-      if not is_unspecified(arg_s):
+      if not isinstance(arg_s, UnspecifiedValue):
         # jax.jit does not allow resharding across different memory kinds even
         # if the argument is uncommitted. Use jax.device_put for those cases,
         # either outside or inside jax.jit.
         if pjit_in_s.memory_kind != arg_s.memory_kind:  # type: ignore
           raise ValueError(
               'Memory kinds passed to jax.jit does not match memory kind on the'
               f' respective arg. Got pjit memory kind: {pjit_in_s.memory_kind}, '  # type: ignore
-              f'arg memory kind: {arg_s.memory_kind} for '  # pytype: disable=attribute-error
+              f'arg memory kind: {arg_s.memory_kind} for '
               f'arg shape: {shaped_abstractify(arg).str_short()}')
         if (committed and
             not isinstance(arg_s, PmapSharding) and
             not op_shardings.are_op_shardings_equal(
                 pjit_in_s._to_xla_hlo_sharding(arg.ndim),  # type: ignore
-                arg_s._to_xla_hlo_sharding(arg.ndim))):  # type: ignore
+                arg_s._to_xla_hlo_sharding(arg.ndim))):
           raise ValueError('Sharding passed to pjit does not match the sharding '
                            'on the respective arg. '
                            f'Got pjit sharding: {pjit_in_s},\n'