Update to node-source-walk@4

Author: realityking

package.json

@@ -40,6 +40,6 @@
   "dependencies": {
     "debug": "^3.1.0",
     "gonzales-pe": "^4.2.3",
-    "node-source-walk": "^3.2.0"
+    "node-source-walk": "^4.0.0"
   }
 }