Bump sfxpython version to 0.4.0

Author: jeffreyc-splunk

python/setup.py

@@ -3,7 +3,7 @@
 # yapf: disable
 setup(
     name="sfxpython",
-    version="0.3.4",
+    version="0.4.0",
     author="SignalFx, Inc",
     description="Python packages used by the Python extension mechanism of the SignalFx Smart Agent",
     url="https://github.com/signalfx/signalfx-agent",