Update cryptography to 2.1.3

[pyup-bot]

There's a new version of cryptography available.
You are currently using 2.0.3. I have updated it to 2.1.3

These links might come in handy: PyPI | Changelog | Repo

Changelog

2.1.2

• Corrected a bug with the manylinux1 wheels where OpenSSL's stack was
  marked executable.

.. _v2-1-1:

2.1.1

• Fixed support for install with the system pip on Ubuntu 16.04.

.. _v2-1:

2.1

• FINAL DEPRECATION Python 2.6 support is deprecated, and will be removed
  in the next release of cryptography.
• BACKWARDS INCOMPATIBLE: Whirlpool, RIPEMD160, and
  UnsupportedExtension have been removed in accordance with our
  :doc:/api-stability policy.
• BACKWARDS INCOMPATIBLE:
  :attr:DNSName.value <cryptography.x509.DNSName.value>,
  :attr:RFC822Name.value <cryptography.x509.RFC822Name.value>, and
  :attr:UniformResourceIdentifier.value <cryptography.x509.UniformResourceIdentifier.value>
  will now return an :term:A-label string when parsing a certificate
  containing an internationalized domain name (IDN) or if the caller passed
  a :term:U-label to the constructor. See below for additional deprecations
  related to this change.
• Installing cryptography now requires pip 6 or newer.
• Deprecated passing :term:U-label strings to the
  :class:~cryptography.x509.DNSName,
  :class:~cryptography.x509.UniformResourceIdentifier, and
  :class:~cryptography.x509.RFC822Name constructors. Instead, users should
  pass values as :term:A-label strings with idna encoding if necessary.
  This change will not affect anyone who is not processing internationalized
  domains.
• Added support for
  :class:~cryptography.hazmat.primitives.ciphers.algorithms.ChaCha20. In
  most cases users should choose
  :class:~cryptography.hazmat.primitives.ciphers.aead.ChaCha20Poly1305
  rather than using this unauthenticated form.
• Added :meth:~cryptography.x509.CertificateRevocationList.is_signature_valid
  to :class:~cryptography.x509.CertificateRevocationList.
• Support :class:~cryptography.hazmat.primitives.hashes.BLAKE2b and
  :class:~cryptography.hazmat.primitives.hashes.BLAKE2s with
  :class:~cryptography.hazmat.primitives.hmac.HMAC.
• Added support for
  :class:~cryptography.hazmat.primitives.ciphers.modes.XTS mode for
  AES.
• Added support for using labels with
  :class:~cryptography.hazmat.primitives.asymmetric.padding.OAEP when using
  OpenSSL 1.0.2 or greater.
• Improved compatibility with NSS when issuing certificates from an issuer
  that has a subject with non-UTF8String string types.
• Add support for the :class:~cryptography.x509.DeltaCRLIndicator extension.
• Add support for the :class:~cryptography.x509.TLSFeature
  extension. This is commonly used for enabling OCSP Must-Staple in
  certificates.
• Add support for the :class:~cryptography.x509.FreshestCRL extension.

.. _v2-0-3:

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖