Fix F401 flake8 warning (x152 / 268).

This change is mostly autogenerated with:

    $ python -m autoflake --in-place --recursive examples templates transformers utils hubconf.py setup.py

I made minor changes in the generated diff.

transformers/tests/modeling_ctrl_test.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import pdb
 import unittest
 
 from transformers import is_torch_available

transformers/tests/modeling_tf_albert_test.py

@@ -14,7 +14,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import sys
 import unittest
 
 from transformers import AlbertConfig, is_tf_available

transformers/tests/modeling_tf_auto_test.py

@@ -15,7 +15,6 @@
 from __future__ import absolute_import, division, print_function
 
 import logging
-import shutil
 import unittest
 
 from transformers import is_tf_available

transformers/tests/modeling_tf_bert_test.py

@@ -14,7 +14,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import sys
 import unittest
 
 from transformers import BertConfig, is_tf_available

transformers/tests/modeling_tf_common_test.py

@@ -15,16 +15,12 @@
 from __future__ import absolute_import, division, print_function
 
 import copy
-import importlib
-import json
-import logging
 import os
 import random
 import shutil
 import sys
 import tempfile
 import unittest
-import uuid
 
 from transformers import is_tf_available, is_torch_available
 
@@ -39,7 +35,6 @@ if is_tf_available():
     # from transformers.modeling_bert import BertModel, BertConfig, BERT_PRETRAINED_MODEL_ARCHIVE_MAP
 
 if sys.version_info[0] == 2:
-    import cPickle as pickle
 
     class TemporaryDirectory(object):
         """Context manager for tempfile.mkdtemp() so it's usable with "with" statement."""
@@ -53,8 +48,6 @@ if sys.version_info[0] == 2:
 
 
 else:
-    import pickle
-
     TemporaryDirectory = tempfile.TemporaryDirectory
     unicode = str
 

transformers/tests/modeling_tf_ctrl_test.py

@@ -14,7 +14,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import sys
 import unittest
 
 from transformers import CTRLConfig, is_tf_available

transformers/tests/modeling_tf_gpt2_test.py

@@ -14,7 +14,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import sys
 import unittest
 
 from transformers import GPT2Config, is_tf_available

transformers/tests/modeling_tf_openai_gpt_test.py

@@ -14,7 +14,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import sys
 import unittest
 
 from transformers import OpenAIGPTConfig, is_tf_available

transformers/tests/modeling_tf_t5_test.py

@@ -14,7 +14,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import sys
 import unittest
 
 from transformers import T5Config, is_tf_available

transformers/tests/modeling_tf_xlnet_test.py

@@ -14,8 +14,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import json
-import os
 import random
 import unittest
 

transformers/tests/modeling_xlnet_test.py

@@ -14,8 +14,6 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function
 
-import json
-import os
 import random
 import unittest
 

transformers/tests/tokenization_auto_test.py

@@ -15,7 +15,6 @@
 from __future__ import absolute_import, division, print_function
 
 import logging
-import shutil
 import unittest
 
 from transformers import (

transformers/tests/tokenization_bert_japanese_test.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 WordpieceTokenizer

transformers/tests/tokenization_distilbert_test.py

@@ -14,9 +14,7 @@
 # limitations under the License.
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-import os
 import unittest
-from io import open
 
 from transformers.tokenization_distilbert import DistilBertTokenizer
 

transformers/tokenization_bert_japanese.py

@@ -20,7 +20,6 @@ import collections
 import logging
 import os
 import unicodedata
-from io import open
 
 import six
 

transformers/tokenization_distilbert.py

@@ -16,11 +16,8 @@
 
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-import collections
 import logging
-import os
 import unicodedata
-from io import open
 
 from .tokenization_bert import BertTokenizer
 

transformers/tokenization_roberta.py

@@ -15,11 +15,7 @@
 """Tokenization classes for RoBERTa."""
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-import json
 import logging
-import os
-import sys
-from io import open
 
 import regex as re
 

utils/download_glue_data.py

@@ -20,9 +20,7 @@ rm MSRParaphraseCorpus.msi
 
 import argparse
 import os
-import shutil
 import sys
-import tempfile
 import urllib.request
 import zipfile