remove npm cache from travis

jiachen247 · jiachen247 · commit 31a56170003f · 2019-04-10T17:56:04.000+08:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,7 +1,6 @@
 language: node_js
 node_js:
   - 9
-cache: npm
 branches:
   except:
     - /^no-ci.*$/
