chore: update esversion used by jshint

JKRhb · JKRhb · commit e11ad5f8d2b3 · 2021-09-21T04:32:55.000+02:00
diff --git a/package.json b/package.json
@@ -34,7 +34,8 @@
     "immed": true,
     "nonbsp": true,
     "strict": true,
-    "loopfunc": true
+    "loopfunc": true,
+    "esversion": 6
   },
   "license": "MIT",
   "repository": {
