chore(package): update eslint to version 6.7.2

Closes #11

Author: greenkeeper[bot]

package.json

@@ -32,7 +32,7 @@
   "repository": "developit/preact-slots",
   "license": "MIT",
   "devDependencies": {
-    "eslint": "^4.16.0",
+    "eslint": "^6.7.2",
     "eslint-config-developit": "^1.1.1",
     "karmatic": "^1.0.6",
     "microbundle": "^0.4.3",