chore(package): update sinon to version 9.0.2

Closes #28

Author: greenkeeper[bot]

package.json

@@ -44,7 +44,7 @@
     "mocha": "^5.2.0",
     "react-hot-loader": "^4.3.12",
     "react-test-renderer": "^16.6.0",
-    "sinon": "^7.1.1",
+    "sinon": "^9.0.2",
     "start-server-and-test": "^1.7.7",
     "webpack": "^4.23.1",
     "webpack-cli": "^3.1.2",