Update dependency shelljs to ^0.8.0 [SECURITY]

Author: renovate[bot]

package.json

@@ -7,7 +7,7 @@
     "chalk": "^1.1.3",
     "eslint-config-airbnb-base": "^11.1.1",
     "eslint-plugin-import": "^2.2.0",
-    "shelljs": "^0.7.7",
+    "shelljs": "^0.8.0",
     "yeoman-generator": "^1.1.1",
     "yosay": "^2.0.0"
   },