py-attrs: updated to 18.2.0

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.

Changes
attrs now ships its own PEP 484 type hints. Together with mypy窶冱 attrs plugin, you窶况e got all you need for writing statically typed code in both Python 2 and 3!
At that occasion, we窶况e also added narrative docs about type annotations in attrs.
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.
The test suite now runs with hypothesis.HealthCheck.too_slow disabled to prevent CI breakage on slower computers.
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.
attr.asdict() now properly handles deeply nested lists and dictionaries.
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.
Fixed a reference leak where the original class would remain live after being replaced when slots=True is set.
Slotted classes can now be made weakly referenceable by passing @attr.s(weakref_slot=True).
Added cache_hash option to @attr.s which causes the hash code to be computed once and stored on the object.
Attributes can be named property and itemgetter now.
It is now possible to override a base class窶� class variable using only class annotations.


(adam)