chore(package): update shx to version 0.3.1

Closes #35

Author: greenkeeper[bot]

package.json

@@ -51,7 +51,7 @@
     "webpack-cli": "^2.0.10",
     "cross-env": "^5.1.3",
     "typescript": "^2.7.2",
-    "shx": "^0.2.2",
+    "shx": "^0.3.1",
     "gzip-size-cli": "^2.1.0"
   },
   "scripts": {