fix(package): update readdir-enhanced to version 5.1.0

Closes #50

Author: greenkeeper[bot]

package.json

@@ -42,7 +42,7 @@
   },
   "dependencies": {
     "bit-mask": "^1.0.1",
-    "readdir-enhanced": "^2.0.0"
+    "readdir-enhanced": "^5.1.0"
   },
   "devDependencies": {
     "chai": "^4.1.2",