add nbformat to requirements

amueller · amueller · commit 0ffd4167b28c · 2016-11-10T18:00:45.000-05:00
diff --git a/requirements.txt b/requirements.txt
@@ -5,4 +5,5 @@ liac-arff>=2.1.1dev
 xmltodict
 nose
 requests
-scikit-learn
+scikit-learn
+nbformat
