chore(package): update sinon to version 9.0.0

Author: greenkeeper[bot]

package.json

@@ -43,7 +43,7 @@
     "postcss-simple-vars": "^5.0.0",
     "proxyquire": "^2.0.0",
     "semantic-release": "^17.0.0",
-    "sinon": "^8.0.0",
+    "sinon": "^9.0.0",
     "tempy": "^0.4.0",
     "xo": "^0.26.0"
   },