Update attrs to 18.2.0

[pyup-bot]

This PR updates attrs from 18.1.0 to 18.2.0.

Changelog

18.2.0

-------------------

Deprecations
^^^^^^^^^^^^

- Comparing subclasses using ``<``, ``>``, ``<=``, and ``>=`` is now deprecated.
The docs always claimed that instances are only compared if the types are identical, so this is a first step to conform to the docs.

Equality operators (``==`` and ``!=``) were always strict in this regard.
`394 <https://github.com/python-attrs/attrs/issues/394>`_


Changes
^^^^^^^

- ``attrs`` now ships its own `PEP 484 <https://www.python.org/dev/peps/pep-0484/>`_ type hints.
Together with `mypy <http://mypy-lang.org>`_'s ``attrs`` plugin, you've got all you need for writing statically typed code in both Python 2 and 3!

At that occasion, we've also added `narrative docs <https://www.attrs.org/en/stable/types.html>`_ about type annotations in ``attrs``.
`238 <https://github.com/python-attrs/attrs/issues/238>`_
- Added *kw_only* arguments to ``attr.ib`` and ``attr.s``, and a corresponding *kw_only* attribute to ``attr.Attribute``.
This change makes it possible to have a generated ``__init__`` with keyword-only arguments on Python 3, relaxing the required ordering of default and non-default valued attributes.
`281 <https://github.com/python-attrs/attrs/issues/281>`_,
`411 <https://github.com/python-attrs/attrs/issues/411>`_
- The test suite now runs with ``hypothesis.HealthCheck.too_slow`` disabled to prevent CI breakage on slower computers.
`364 <https://github.com/python-attrs/attrs/issues/364>`_,
`396 <https://github.com/python-attrs/attrs/issues/396>`_
- ``attr.validators.in_()`` now raises a ``ValueError`` with a useful message even if the options are a string and the value is not a string.
`383 <https://github.com/python-attrs/attrs/issues/383>`_
- ``attr.asdict()`` now properly handles deeply nested lists and dictionaries.
`395 <https://github.com/python-attrs/attrs/issues/395>`_
- Added ``attr.converters.default_if_none()`` that allows to replace ``None`` values in attributes.
For example ``attr.ib(converter=default_if_none(""))`` replaces ``None`` by empty strings.
`400 <https://github.com/python-attrs/attrs/issues/400>`_,
`414 <https://github.com/python-attrs/attrs/issues/414>`_
- Fixed a reference leak where the original class would remain live after being replaced when ``slots=True`` is set.
`407 <https://github.com/python-attrs/attrs/issues/407>`_
- Slotted classes can now be made weakly referenceable by passing ``attr.s(weakref_slot=True)``.
`420 <https://github.com/python-attrs/attrs/issues/420>`_
- Added *cache_hash* option to ``attr.s`` which causes the hash code to be computed once and stored on the object.
`425 <https://github.com/python-attrs/attrs/issues/425>`_
- Attributes can be named ``property`` and ``itemgetter`` now.
`430 <https://github.com/python-attrs/attrs/issues/430>`_
- It is now possible to override a base class' class variable using only class annotations.
`431 <https://github.com/python-attrs/attrs/issues/431>`_


----

Links

• PyPI: https://pypi.org/project/attrs
• Changelog: https://pyup.io/changelogs/attrs/
• Homepage: https://www.attrs.org/

[coveralls]

Coverage remained the same at 83.968% when pulling 6f1405f on pyup-update-attrs-18.1.0-to-18.2.0 into 1cfa8d5 on master.