Merge pull request #405 from halfzebra/renovate/whatwg-fetch-3.x

fix(package.json): Update dependency whatwg-fetch to v3

Author: halfzebra

package.json

@@ -64,7 +64,7 @@
     "webpack": "4.43.0",
     "webpack-dev-server": "3.10.3",
     "webpack-manifest-plugin": "2.2.0",
-    "whatwg-fetch": "2.0.4",
+    "whatwg-fetch": "3.0.0",
     "workbox-webpack-plugin": "4.3.1"
   },
   "devDependencies": {