Remove unittest.main() in test modules.

This construct isn't used anymore these days.

Running python tests/test_foo.py puts the tests/ directory on
PYTHONPATH, which isn't representative of how we run tests.

Use python -m unittest tests/test_foo.py instead.

templates/adding_a_new_model/tests/test_modeling_tf_xxx.py

@@ -14,8 +14,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import unittest
-
 from transformers import XxxConfig, is_tf_available
 
 from .test_configuration_common import ConfigTester
@@ -251,7 +249,3 @@ class TFXxxModelTest(TFCommonTestCases.TFCommonModelTester):
         for model_name in ["xxx-base-uncased"]:
             model = TFXxxModel.from_pretrained(model_name, cache_dir=CACHE_DIR)
             self.assertIsNotNone(model)
-
-
-if __name__ == "__main__":
-    unittest.main()

templates/adding_a_new_model/tests/test_modeling_xxx.py

@@ -14,8 +14,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import unittest
-
 from transformers import is_torch_available
 
 from .test_configuration_common import ConfigTester
@@ -272,7 +270,3 @@ class XxxModelTest(CommonTestCases.CommonModelTester):
         for model_name in list(XXX_PRETRAINED_MODEL_ARCHIVE_MAP.keys())[:1]:
             model = XxxModel.from_pretrained(model_name, cache_dir=CACHE_DIR)
             self.assertIsNotNone(model)
-
-
-if __name__ == "__main__":
-    unittest.main()

templates/adding_a_new_model/tests/test_tokenization_xxx.py

@@ -15,7 +15,6 @@
 from __future__ import absolute_import, division, print_function, unicode_literals
 
 import os
-import unittest
 from io import open
 
 from transformers.tokenization_bert import VOCAB_FILES_NAMES, XxxTokenizer
@@ -63,7 +62,3 @@ class XxxTokenizationTest(CommonTestCases.CommonTokenizerTester):
         tokens = tokenizer.tokenize("UNwant\u00E9d,running")
         self.assertListEqual(tokens, ["un", "##want", "##ed", ",", "runn", "##ing"])
         self.assertListEqual(tokenizer.convert_tokens_to_ids(tokens), [7, 4, 5, 10, 8, 9])
-
-
-if __name__ == "__main__":
-    unittest.main()