tools: add python future module
diff --git a/requirements.txt b/requirements.txt
index 5f27f9b..d99d87f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,6 +3,7 @@
 cffi==1.11.5
 cryptography==2.4.2
 fabric==2.4.0
+future==0.17.1
 idna==2.8
 invoke==1.2.0
 paramiko==2.4.2