chore(package): update sinon to version 7.3.0

Closes #106

Author: greenkeeper[bot]

Diff for: package.json

@@ -59,7 +59,7 @@
     "mocha": "^5.1.1",
     "mocha-typescript": "^1.1.14",
     "nyc": "^12.0.2",
-    "sinon": "^6.0.1",
+    "sinon": "^7.3.0",
     "ts-node": "^7.0.1",
     "tslint": "^5.10.0",
     "tslint-config-standard": "^8.0.0",