Better TF docstring types (#23477)

* Rework TF type hints to use | None instead of Optional[] for tf.Tensor

* Rework TF type hints to use | None instead of Optional[] for tf.Tensor

* Don't forget the imports

* Add the imports to tests too

* make fixup

* Refactor tests that depended on get_type_hints

* Better test refactor

* Fix an old hidden bug in the test_keras_fit input creation code

* Fix for the Deit tests

tests/models/deit/test_modeling_tf_deit.py

@@ -15,6 +15,8 @@
 """ Testing suite for the TensorFlow DeiT model. """
 
 
+from __future__ import annotations
+
 import inspect
 import unittest
 
@@ -242,7 +244,7 @@ class TFDeiTModelTest(TFModelTesterMixin, PipelineTesterMixin, unittest.TestCase
         inputs_dict = super()._prepare_for_class(inputs_dict, model_class, return_labels=return_labels)
 
         if return_labels:
-            if model_class.__name__ == "DeiTForImageClassificationWithTeacher":
+            if "labels" in inputs_dict and "labels" not in inspect.signature(model_class.call).parameters:
                 del inputs_dict["labels"]
 
         return inputs_dict