chore(package): update fetch-mock to version 8.0.0

Author: greenkeeper[bot]

package.json

@@ -40,7 +40,7 @@
     "@types/fetch-mock": "^7.2.5",
     "@types/jest": "^24.0.13",
     "@types/node": "^12.0.2",
-    "fetch-mock": "^7.3.1",
+    "fetch-mock": "^8.0.0",
     "jest": "^24.8.0",
     "prettier": "^1.17.1",
     "semantic-release": "^15.13.3",