chore(deps): update dependency sinon to v7 (googleapis#449)

Author: renovate[bot]

handwritten/storage/samples/package.json

@@ -32,6 +32,6 @@
     "mocha": "^5.2.0",
     "nyc": "^13.0.0",
     "proxyquire": "^2.0.1",
-    "sinon": "^6.0.1"
+    "sinon": "^7.0.0"
   }
 }