chore: bump version to v0.4.0

Author: sveneberth

src/viur/shop/version.py

@@ -2,7 +2,7 @@
 # For pre-releases, postfix with ".betaN" or ".rcN" where `N` is an incremented number for each pre-release.
 # This will mark it as a pre-release as well on PyPI.
 
-__version__ = "0.3.1"
+__version__ = "0.4.0"
 
 assert __version__.count(".") >= 2 and "".join(__version__.split(".", 3)[:3]).isdigit(), \
     "Semantic __version__ expected!"