Release 0.4.0

Signed-off-by: Brian Brazil <brian.brazil@robustperception.io>

Author: brian-brazil

setup.py

@@ -2,7 +2,7 @@
 
 setup(
     name="prometheus_client",
-    version="0.3.1",
+    version="0.4.0",
     author="Brian Brazil",
     author_email="brian.brazil@robustperception.io",
     description="Python client for the Prometheus monitoring system.",