upgrade eslint dependency version on package.json to address security alert

Author: samdengler

package.json

@@ -6,7 +6,7 @@
   "devDependencies": {
     "babel-eslint": "^7.2.3",
     "concurrent-transform": "^1.0.0",
-    "eslint": "^3.19.0",
+    "eslint": ">=4.18.2",
     "eslint-config-airbnb": "^14.1.0",
     "eslint-plugin-babel": "^4.1.1",
     "eslint-plugin-import": "^2.2.0",