update .travis.yml

HariSekhon · HariSekhon · commit a1273baa9ef1 · 2017-10-17T12:16:20.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -39,6 +39,8 @@ branches:
   only:
     - master
 
+cache: pip
+
 services:
   - docker
 
