Added Cython to Pipfile and Changed runtime.txt back to using python 3.6.4

ursulahuang · ursulahuang · commit 220f1130cecc · 2020-06-23T16:35:09.000-04:00
diff --git a/Pipfile b/Pipfile
@@ -42,6 +42,7 @@ gunicorn = "*"
 "psycopg2" = "*"
 pygithub = "*"
 py-trello = "*"
+cython="*"
 ddtrace = "*"
 coveralls = "*"
 python-dotenv = "*"
diff --git a/Pipfile.lock b/Pipfile.lock
diff --git a/runtime.txt b/runtime.txt
@@ -1 +1 @@
-python-3.7.7
+python-3.6.4
