export type annotations in package (#679)

* export type annotations via our pypi package

* update CHANGELOG

Co-authored-by: Pieter Marsman <pietermarsman@gmail.com>

CHANGELOG.md

@@ -6,6 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Unreleased]
 
 ### Added
+- Export type annotations from pypi package per PEP561 ([#679](https://github.com/pdfminer/pdfminer.six/pull/679))
 - Support for identity cmap's ([#626](https://github.com/pdfminer/pdfminer.six/pull/626))
 
 ### Fixed

setup.py

@@ -11,7 +11,7 @@ setup(
     name='pdfminer.six',
     version=package.__version__,
     packages=['pdfminer'],
-    package_data={'pdfminer': ['cmap/*.pickle.gz']},
+    package_data={'pdfminer': ['cmap/*.pickle.gz', 'py.typed']},
     install_requires=[
         'chardet ; python_version > "3.0"',
         'cryptography',