Fix `EncodecModelTest::test_multi_gpu_data_parallel_forward` (#24663)

fix
Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>

tests/models/encodec/test_modeling_encodec.py

@@ -73,7 +73,8 @@ class EncodecModelTester:
     def __init__(
         self,
         parent,
-        batch_size=13,
+        # `batch_size` needs to be an even number if the model has some outputs with batch dim != 0.
+        batch_size=12,
         num_channels=2,
         is_training=False,
         num_hidden_layers=4,