chore(package): update standard-version to version 7.1.0

Closes #16

Author: greenkeeper[bot]

package.json

@@ -44,7 +44,7 @@
     "jshint": "^2.9.4",
     "mocha": "*",
     "shelljs": "^0.7.5",
-    "standard-version": "4.2.0",
+    "standard-version": "7.1.0",
     "through2": "^2.0.3"
   },
   "dependencies": {