Update node versions in package.json to match currently maintained node versions

Author: lukemelia

.travis.yml

@@ -3,7 +3,7 @@ language: node_js
 node_js:
   # we recommend testing addons with the same minimum supported node version as Ember CLI
   # so that your addon works for all apps
-  - "4"
+  - "6"
 
 sudo: required
 dist: trusty
@@ -20,6 +20,7 @@ env:
   - EMBER_TRY_SCENARIO=ember-lts-2.8
   - EMBER_TRY_SCENARIO=ember-lts-2.12
   - EMBER_TRY_SCENARIO=ember-lts-2.18
+  - EMBER_TRY_SCENARIO=ember-lts-3.4
   - EMBER_TRY_SCENARIO=ember-release
   - EMBER_TRY_SCENARIO=ember-beta
   - EMBER_TRY_SCENARIO=ember-canary

package.json

@@ -49,7 +49,7 @@
     "loader.js": "^4.2.3"
   },
   "engines": {
-    "node": "^4.5 || 6.* || >= 7.*"
+    "node": "6.* || 8.* || 10.* || >= 12.*"
   },
   "ember-addon": {
     "configPath": "tests/dummy/config"