chore(package): update sinon to version 8.1.0

Closes #106

Author: greenkeeper[bot]

Diff for: package.json

@@ -70,7 +70,7 @@
     "mocha-typescript": "^1.1.14",
     "nyc": "^13.1.0",
     "puppeteer": "^1.19.0",
-    "sinon": "^6.0.1",
+    "sinon": "^8.1.0",
     "source-map-support": "^0.5.6",
     "ts-loader": "^6.1.0",
     "ts-node": "^7.0.1",