Bump supertest from 6.0.0 to 6.1.3 in /frontend

Bumps [supertest](https://github.com/visionmedia/supertest) from 6.0.0 to 6.1.3.
- [Release notes](https://github.com/visionmedia/supertest/releases)
- [Commits](ladjs/supertest@v6.0.0...v6.1.3)

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

frontend/package.json

@@ -79,7 +79,7 @@
     "react-hot-loader": "^4.13.0",
     "react-test-renderer": "^16.14.0",
     "source-map-loader": "^2.0.1",
-    "supertest": "^6.0.0",
+    "supertest": "^6.1.3",
     "url-loader": "^4.1.1",
     "webpack": "^5.0.2",
     "webpack-cli": "^4.1.0",