Bump to version 0.4.1 (#541)

Author: fritzo

setup.py

@@ -23,7 +23,7 @@
 
 setup(
     name="funsor",
-    version="0.4.0",
+    version="0.4.1",
     description="A tensor-like library for functions and distributions",
     packages=find_packages(include=["funsor", "funsor.*"]),
     url="https://github.com/pyro-ppl/funsor",