Bump superagent from 3.8.3 to 6.1.0

Bumps [superagent](https://github.com/visionmedia/superagent) from 3.8.3 to 6.1.0.
- [Release notes](https://github.com/visionmedia/superagent/releases)
- [Changelog](https://github.com/visionmedia/superagent/blob/master/HISTORY.md)
- [Commits](ladjs/superagent@v3.8.3...v6.1.0)

---
updated-dependencies:
- dependency-name: superagent
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

DNN Platform/Modules/ResourceManager/ResourceManager.Web/package.json

@@ -66,7 +66,7 @@
     "redux-immutable-state-invariant": "^2.1.0",
     "redux-thunk": "^2.3.0",
     "style-loader": "0.23.1",
-    "superagent": "^3.2.1",
+    "superagent": "^6.1.0",
     "url-loader": "1.1.2"
   }
 }