chore(package): update fetch-mock to version 9.0.0

Author: greenkeeper[bot]

package.json

@@ -49,7 +49,7 @@
     "@types/node": "^13.1.0",
     "btoa-lite": "^1.0.0",
     "chai": "^4.1.2",
-    "fetch-mock": "^8.3.2",
+    "fetch-mock": "^9.0.0",
     "jest": "^25.1.0",
     "prettier": "^1.14.2",
     "proxy": "^1.0.0",