20.3.0
Prepare 20.3.0
Add types to collect_by_mro annotations m(
Fix exception chaining on PyPy (#712)
Move package into src directory
Treat frozensets like sets in asdict/astuple (#704)
Add hooks for field transformation and for asdict serialization (#653)
Rename _version.py into _version_info.py
Rename converters.chain to converters.pipe
Add on_setattr hooks to attr.s and attr.ib (#660)
Add default_role for Sphinx. (#571)
Fixes generics in mypy types (#443)
Add PEP484 stubs (#238)
fix comment typo
Fix some typing issues (#581)