chore(deps): update dependency fetch-mock to v8

Author: renovate-bot

packages/sync/package.json

@@ -40,7 +40,7 @@
     "@types/ws": "6.0.3",
     "chai": "4.2.0",
     "del": "5.1.0",
-    "fetch-mock": "7.7.2",
+    "fetch-mock": "8.0.0",
     "graphql": "14.5.8",
     "graphql-tag": "2.10.1",
     "mocha": "6.2.2",