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

Closes #39

Author: greenkeeper[bot]

package.json

@@ -32,7 +32,7 @@
   "dependencies": {
     "@types/chai": "^4.2.4",
     "@types/mocha": "^5.2.7",
-    "@types/sinon": "^7.5.0",
+    "@types/sinon": "^9.0.4",
     "@types/sinon-chai": "^3.2.3",
     "chai": "^4.2.0",
     "mocha": "^6.2.2",