[build] format travis.yml

.travis.yml

@@ -3,7 +3,7 @@ sudo: required
 addons:
   chrome: stable
 node_js:
-- 10
+  - 10
 os: linux
 cache:
   yarn: true
@@ -12,11 +12,11 @@ branches:
     - master
     - dev
 install:
-- |
+  - |
     yarn install
 script:
-- |
+  - |
     npm run lint && npm run test
 after_success:
-- |
+  - |
     cat ./test/coverage/lcov.info | ./node_modules/.bin/codecov