Attempt to fix Python 3.3 build failure (#163)

juanshishido · jbabichjapan · commit be98002fc892 · 2018-03-20T17:16:34.000+09:00
https://travis-ci.org/twitterdev/twitter-python-ads-sdk/jobs/355605475 pypa/setuptools-scm#209
diff --git a/requirements.txt b/requirements.txt
@@ -4,3 +4,4 @@ python-dateutil
 sphinx==1.3.1
 responses
 mock
+setuptools_scm
