Update submodule version to 3.1

Signed-off-by: Deokgyu Yang <secugyu@gmail.com>
diff --git a/setup.py b/setup.py
index 9b0fe45..83519c9 100644
--- a/setup.py
+++ b/setup.py
@@ -57,7 +57,7 @@
 
 setup(
     name = 'odroid_wiringpi',
-    version = '3.0',
+    version = '3.1',
     ext_modules = [ _odroid_wiringpi ],
     py_modules = ["odroid_wiringpi"],
     install_requires=[],