Bump version to 2.0.31

CHANGES.rst

@@ -6,7 +6,7 @@ This is a record of changes made between each Mutalyzer release.
 Version 2.0.31
 ---------------
 
-Release date to be decided.
+Released on August 21st 2019.
 
 - Update requirements (`#486
   <https://github.com/mutalyzer/mutalyzer/pull/486>`_).

mutalyzer/__init__.py

@@ -21,8 +21,8 @@ from __future__ import unicode_literals
 # [1] http://peak.telecommunity.com/DevCenter/setuptools#specifying-your-project-s-version
 # [2] http://semver.org/
 
-__version_info__ = ('2', '0', '31', 'dev')
-__date__ = '24 May 2019'
+__version_info__ = ('2', '0', '31')
+__date__ = '21 August 2019'
 
 
 __version__ = '.'.join(__version_info__)