Update .travis.yml

Author: krystianity

.travis.yml

@@ -1,5 +1,8 @@
 language: node_js
 node_js:
-  - "11"
+  - "12"
 script:
-  - npm run test-ci
+  - rm -rf node_modules
+  - yarn
+  - yarn add --frozen-lockfile [email protected]
+  - yarn test-ci