chore(package): update standard-version to version 5.0.2

Closes #26

Author: greenkeeper[bot]

package.json

@@ -41,7 +41,7 @@
     "koa": "^2.5.0",
     "nyc": "^12.0.1",
     "shelljs": "^0.8.1",
-    "standard-version": "^4.3.0",
+    "standard-version": "^5.0.2",
     "supertest": "^3.0.0",
     "tslint": "^5.9.1",
     "typescript": "^2.8.1"