Bump bugfix number.

Author: greschd

tbmodels/__init__.py

@@ -4,7 +4,7 @@
 TBmodels is a tool for creating / loading and manipulating tight-binding models.
 """
 
-__version__ = '1.3.0'
+__version__ = '1.3.1'
 
 # import order is important due to circular imports
 from . import helpers