chore(package): update @types/sinon to version 9.0.4

Closes #156

Author: greenkeeper[bot]

package.json

@@ -37,7 +37,7 @@
   "devDependencies": {
     "@types/chai": "4.2.0",
     "@types/mocha": "5.2.7",
-    "@types/sinon": "7.0.13",
+    "@types/sinon": "9.0.4",
     "chai": "4.2.0",
     "gulp": "4.0.2",
     "gulp-istanbul": "1.1.3",