[pytes collection] Fix flax test collection (#34004)

bit weird but to filter I had to use this

tests/models/mbart/test_modeling_flax_mbart.py

@@ -116,6 +116,7 @@ class FlaxMBartModelTester(unittest.TestCase):
         self.bos_token_id = bos_token_id
         self.decoder_start_token_id = decoder_start_token_id
         self.initializer_range = initializer_range
+        super().__init__()
 
     def prepare_config_and_inputs(self):
         input_ids = np.clip(ids_tensor([self.batch_size, self.seq_length - 1], self.vocab_size), 3, self.vocab_size)