Changes 8.1.0:

* 1473: ``HTTPError`` now also works as a context manager.

* 1487: The sessions tool now accepts a ``storage_class``
  parameter, which supersedes the new deprecated
  ``storage_type`` parameter. The ``storage_class`` should
  be the actual Session subclass to be used.

* Releases now use ``setuptools_scm`` to track the release
  versions. Therefore, releases can be cut by simply tagging
  a commit in the repo. Versions numbers are now stored in
  exactly one place.

(adam)