fix(package): update chevrotain to version 6.2.0

Closes #36

Author: greenkeeper[bot]

package.json

@@ -50,7 +50,7 @@
     "traverse": "0.6.6"
   },
   "dependencies": {
-    "chevrotain": "3.7.2",
+    "chevrotain": "6.2.0",
     "lodash": "4.17.11"
   }
 }