Fix a TF test name (LayoutLMModelTest) (#16061)

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

tests/layoutlm/test_modeling_tf_layoutlm.py

@@ -196,7 +196,7 @@ class TFLayoutLMModelTester:
 
 
 @require_tf
-class LayoutLMModelTest(TFModelTesterMixin, unittest.TestCase):
+class TFLayoutLMModelTest(TFModelTesterMixin, unittest.TestCase):
 
     all_model_classes = (
         (TFLayoutLMModel, TFLayoutLMForMaskedLM, TFLayoutLMForTokenClassification, TFLayoutLMForSequenceClassification)