Update for python 3.7.

Author: yxd-hde

setup.py

@@ -38,7 +38,7 @@ def run_tests(self):
           'Operating System :: POSIX',
           'Programming Language :: Python',
           'Programming Language :: Python :: 2.7',
-          'Programming Language :: Python :: 3.6',
+          'Programming Language :: Python :: 3.7',
           'License :: OSI Approved :: MIT License'
       ],
       keywords="AWS Lambda",

wercker.yml

@@ -1,4 +1,4 @@
-box: python:2.7-slim
+box: python:3.7-slim
 
 build:
   steps:
@@ -32,7 +32,7 @@ build-py2:
           python setup.py test
 
 build-py3:
-  box: python:3.6-slim
+  box: python:3.7-slim
   steps:
     - script:
         name: virtualenv install