chore: remove ci coverage

Author: pemrouz

.travis.yml

@@ -1,6 +1,4 @@
 sudo: false
 language: node_js
 node_js:
-  - "stable"
-
-after_script: NODE_ENV=test istanbul cover ./node_modules/mocha/bin/_mocha --report lcovonly -- -R spec && cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js && rm -rf ./coverage
+  - "stable"