chore(package): update sinon to version 7.5.0

Closes #61

Author: greenkeeper[bot]

package.json

@@ -69,7 +69,7 @@
     "react": "^0.14 || ^15 || ^16",
     "react-dom": "^0.14 || ^15 || ^16",
     "rimraf": "^2.6.2",
-    "sinon": "^6.1.5",
+    "sinon": "^7.5.0",
     "sinon-sandbox": "^2.0.0"
   },
   "engines": {