Update Node testing to current release schedule

Author: jakezatecky

.travis.yml

@@ -2,7 +2,7 @@ language: node_js
 node_js:
   - '8'
   - '10'
-  - '11'
+  - '12'
 before_script:
   # Remove ./node_modules/.bin from PATH so node-which doesn't replace Unix which and cause RVM to barf. See https://github.com/travis-ci/travis-ci/issues/5092
   - PATH=${PATH//:\.\/node_modules\/\.bin/}