crypto: CryptographyDeprecationWarning on PyPy 2 triggers a WrongEncryptionPassword exception

[decalage2]

Today the tests running on PyPy 2 trigger the following error on PyPy 2 (but not CPython 2):

/home/travis/virtualenv/pypy2.7-7.1.1/site-packages/msoffcrypto/method/rc4.py:5: CryptographyDeprecationWarning: Python 2 is no longer supported by the Python core team. Support for it is now deprecated in cryptography, and will be removed in a future release.
  from cryptography.hazmat.backends import default_backend
msodde 0.55 - http://decalage.info/python/oletools
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Opening file: /home/travis/build/decalage2/oletools/tests/test-data/encrypted/dde-test-encrypt-standardpassword.xls
ERROR    Decrypt failed, run with debug output to get details
ERROR    Given passwords could not decrypt office file /home/travis/build/decalage2/oletools/tests/test-data/encrypted/dde-test-encrypt-standardpassword.xls, use option -p to specify the password
Traceback (most recent call last):
  File "/home/travis/build/decalage2/oletools/oletools/msodde.py", line 994, in main
    field_filter_mode=args.field_filter_mode)
  File "/home/travis/build/decalage2/oletools/oletools/msodde.py", line 955, in process_maybe_encrypted
    raise crypto.WrongEncryptionPassword(filepath)
WrongEncryptionPassword: Given passwords could not decrypt office file /home/travis/build/decalage2/oletools/tests/test-data/encrypted/dde-test-encrypt-standardpassword.xls, use option -p to specify the password

[christian-intra2net]

I encountered this warning with CPython 2 as well, I think msoffcrypto should not be a required dependency for any python2-version (see #795)

However, cryptography will currently still be installed through other dependencies, so this is no solution to the problem