Update cryptography to 2.6.1

[pyup-bot]

This PR updates cryptography from 2.5 to 2.6.1.

Changelog

2.6.1

~~~~~~~~~~~~~~~~~~

* Resolved an error in our build infrastructure that broke our Python3 wheels
for macOS and Linux.

.. _v2-6:

2.6

~~~~~~~~~~~~~~~~

* **BACKWARDS INCOMPATIBLE:** Removed
``cryptography.hazmat.primitives.asymmetric.utils.encode_rfc6979_signature``
and
``cryptography.hazmat.primitives.asymmetric.utils.decode_rfc6979_signature``,
which had been deprecated for nearly 4 years. Use
:func:`~cryptography.hazmat.primitives.asymmetric.utils.encode_dss_signature`
and
:func:`~cryptography.hazmat.primitives.asymmetric.utils.decode_dss_signature`
instead.
* **BACKWARDS INCOMPATIBLE**: Removed ``cryptography.x509.Certificate.serial``,
which had been deprecated for nearly 3 years. Use
:attr:`~cryptography.x509.Certificate.serial_number` instead.
* Updated Windows, macOS, and ``manylinux1`` wheels to be compiled with
OpenSSL 1.1.1b.
* Added support for :doc:`/hazmat/primitives/asymmetric/ed448` when using
OpenSSL 1.1.1b or newer.
* Added support for :doc:`/hazmat/primitives/asymmetric/ed25519` when using
OpenSSL 1.1.1b or newer.
* :func:`~cryptography.hazmat.primitives.serialization.load_ssh_public_key` can
now load ``ed25519`` public keys.
* Add support for easily mapping an object identifier to its elliptic curve
class via
:func:`~cryptography.hazmat.primitives.asymmetric.ec.get_curve_for_oid`.
* Add support for OpenSSL when compiled with the ``no-engine``
(``OPENSSL_NO_ENGINE``) flag.

.. _v2-5:

Links

• PyPI: https://pypi.org/project/cryptography
• Changelog: https://pyup.io/changelogs/cryptography/
• Repo: https://github.com/pyca/cryptography