build(deps-dev): bump supertest from 6.1.3 to 6.1.6

Bumps [supertest](https://github.com/visionmedia/supertest) from 6.1.3 to 6.1.6.
- [Release notes](https://github.com/visionmedia/supertest/releases)
- [Commits](https://github.com/visionmedia/supertest/compare/v6.1.3...v6.1.6)

---
updated-dependencies:
- dependency-name: supertest
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

plugins/azure-devops-backend/package.json

@@ -33,7 +33,7 @@
   "devDependencies": {
     "@backstage/cli": "^0.10.2",
     "@types/supertest": "^2.0.8",
-    "supertest": "^4.0.2",
+    "supertest": "^6.1.6",
     "msw": "^0.35.0"
   },
   "files": [