Update version number to 0.3.0

Author: hanyazou

setup.py

@@ -10,7 +10,7 @@
 setup(
     name='tellopy',
 
-    version='0.3.0.dev0',
+    version='0.3.0',
 
     description='DJI Tello drone controller',
     url='https://github.com/hanyazou/TelloPy',