chore(deps): update dependency memory-fs to ^0.5.0

Author: renovate-bot

package.json

@@ -59,7 +59,7 @@
     "grumbler-scripts": "^3",
     "imagemagick": "^0.1.3",
     "imgur": "^0.2.1",
-    "memory-fs": "^0.4.1",
+    "memory-fs": "^0.5.0",
     "mocha": "^4",
     "mocketeer": "^0.3.0",
     "pixelmatch": "^4.0.2",