[pygobject] Created tag 3.31.4

[Christoph Reiter <creiter src gnome org>]

The signed tag '3.31.4' was created.

Tagger: Christoph Reiter <reiter christoph gmail com>
Date: 1551946350 +0100

    release 3.31.4

Changes since the last tag '3.31.3':

Christoph Reiter (11):
      version bump
      ci: update to PyPy 7.0 and update CPython to the latest stable releases
      ci: enable pycairo for PyPy
      getting started: add a note for the tutorial and the API reference
      GTK+ -> GTK
      tests: add tests for GObject.Object.weak_ref
      docs: document GObject.Object.weak_ref(). Fixes #245
      docs: update travis-ci example to Ubuntu xenial
      tests: more pygtkcompat coverage
      ci: add pypy3.6
      release

Renato Florentino Garcia (2):
      Add Cairo Pattern foreign struct.
      Add cairo_matrix_t converter to GValue.