chore(package): update eslint to version 6.7.2

Closes #22

Author: greenkeeper[bot]

package.json

@@ -27,7 +27,7 @@
   "license": "MIT",
   "devDependencies": {
     "bundlesize": "^0.17.0",
-    "eslint": "^5.3.0",
+    "eslint": "^6.7.2",
     "eslint-config-developit": "^1.1.1",
     "microbundle": "^0.6.0",
     "preact-cli": "^2.1.0"