chore(package): update eslint to version 5.15.2

Closes #27

Author: greenkeeper[bot]

package.json

@@ -20,7 +20,7 @@
   },
   "devDependencies": {
     "copy-webpack-plugin": "^4.6.0",
-    "eslint": "^4.5.0",
+    "eslint": "^5.15.2",
     "eslint-config-developit": "^1.1.1",
     "preact-cli": "^3.0.0-next.14",
     "preact-cli-plugin-env-vars": "^1.2.1",