chore(deps): bump whatwg-fetch from 2.0.3 to 3.6.20 in /ui

Bumps [whatwg-fetch](https://github.com/github/fetch) from 2.0.3 to 3.6.20.
- [Release notes](https://github.com/github/fetch/releases)
- [Changelog](https://github.com/JakeChampion/fetch/blob/main/CHANGELOG.md)
- [Commits](JakeChampion/fetch@v2.0.3...v3.6.20)

---
updated-dependencies:
- dependency-name: whatwg-fetch
  dependency-version: 3.6.20
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

ui/package-lock.json

@@ -65,7 +65,7 @@
     "webpack": "4.38.0",
     "webpack-dev-server": "4.15.2",
     "webpack-manifest-plugin": "2.0.4",
-    "whatwg-fetch": "2.0.3",
+    "whatwg-fetch": "3.6.20",
     "xterm": "4.1.0"
   },
   "scripts": {