Remove PY2 related stuff from test (#478)

test/common_utils.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import os
 from shutil import copytree
-import backports.tempfile as tempfile
+import tempfile
+
 import torch
 
 TEST_DIR_PATH = os.path.dirname(os.path.realpath(__file__))

test/compliance/generate_fbank_data.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import argparse
 import logging
 import os

test/compliance/generate_test_stft_data.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import argparse
 import logging
 import os

test/compliance/utils.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import random
 import torchaudio
 

test/test.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import unittest
 import common_utils
 import torch

test/test_compliance_kaldi.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import math
 import os
 import common_utils

test/test_dataloader.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import unittest
 import common_utils
 import torch

test/test_functional.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import math
 import os
 

test/test_functional_filtering.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import math
 import os
 import torch

test/test_kaldi_io.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import os
 import torch
 import torchaudio.kaldi_io as kio

test/test_sox_effects.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import unittest
 import common_utils
 import torch

test/test_transforms.py

-from __future__ import absolute_import, division, print_function, unicode_literals
 import math
 import os