Bump superagent from 6.1.0 to 8.1.2

Bumps [superagent](https://github.com/ladjs/superagent) from 6.1.0 to 8.1.2.
- [Release notes](https://github.com/ladjs/superagent/releases)
- [Changelog](https://github.com/ladjs/superagent/blob/master/HISTORY.md)
- [Commits](ladjs/superagent@v6.1.0...v8.1.2)

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

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

package.json

@@ -62,7 +62,7 @@
     "recursive-readdir": "^2.2.3",
     "require-all": "^3.0.0",
     "shelljs": "^0.8.5",
-    "superagent": "^6.1.0",
+    "superagent": "^8.1.2",
     "tv4": "^1.3.0",
     "watchify": "^4.0.0",
     "yankee": "^1.0.8"