Remove caching with Travis

Author: ehmicky

.travis.yml

@@ -42,8 +42,9 @@ jobs:
           tags: true
         # We want to run install step and keep built files for release
         skip_cleanup: true
-cache: npm
 notifications:
   webhooks:
     - https://www.travisbuddy.com?only=failed,errored&insertMode=update
   email: false
+# We do not use `cache: npm` because downloading and uploading the cache
+# actually takes more time than it saves during `npm ci`.