Fix TF nightly tests (#20507)

* Fixed test_saved_model_extended

* Fix TFGPT2 tests

* make fixup

* Make sure keras-nlp utils are available for type hinting too

* Update src/transformers/testing_utils.py

Co-authored-by: Yih-Dar <2521628+ydshieh@users.noreply.github.com>

* make fixup

Co-authored-by: Yih-Dar <2521628+ydshieh@users.noreply.github.com>

src/transformers/testing_utils.py

@@ -57,6 +57,7 @@ from .utils import (
     is_ftfy_available,
     is_ipex_available,
     is_jumanpp_available,
+    is_keras_nlp_available,
     is_librosa_available,
     is_natten_available,
     is_onnx_available,
@@ -392,6 +393,13 @@ def require_tensorflow_text(test_case):
     return unittest.skipUnless(is_tensorflow_text_available(), "test requires tensorflow_text")(test_case)
 
 
+def require_keras_nlp(test_case):
+    """
+    Decorator marking a test that requires keras_nlp. These tests are skipped when keras_nlp isn't installed.
+    """
+    return unittest.skipUnless(is_keras_nlp_available(), "test requires keras_nlp")(test_case)
+
+
 def require_pandas(test_case):
     """
     Decorator marking a test that requires pandas. These tests are skipped when pandas isn't installed.