fix(package): update del to version 4.1.1

Closes #64

Author: greenkeeper[bot]

package.json

@@ -38,7 +38,7 @@
     "cpy": "^7.0.0",
     "cross-env": "^5.1.1",
     "cross-spawn": "^5.1.0",
-    "del": "^3.0.0",
+    "del": "^4.1.1",
     "express": "^4.16.2",
     "get-port": "^3.2.0",
     "globby": "^7.1.1",