Log Message:
py-subunit: updated to 1.4.0

1.4.0

IMPROVEMENTS
* Drop Python 3.3 support, and test on 3.5 and 3.6.
* Add support for Python 3.7 and 3.8.
* Improve readability of SubUnit v2 spec.
* Add license to setup.py.

BUGFIXES
* Migrate Gtk interface to GObject introspection.
* Fix file open for python3.
* Check written bytes are not None before summing them to offset.
* Correctly handle py3 RawIOBase read().