Bump package version to 1.6.0

Author: pglombardo

setup.py

@@ -20,7 +20,7 @@ def check_setuptools():
 check_setuptools()
 
 setup(name='instana',
-      version='1.5.0',
+      version='1.6.0',
       download_url='https://github.com/instana/python-sensor',
       url='https://www.instana.com/',
       license='MIT',