build(deps): bump esbuild, @vitest/coverage-v8 and vitest in /backend

Bumps [esbuild](https://github.com/evanw/esbuild) to 0.27.2 and updates ancestor dependencies [esbuild](https://github.com/evanw/esbuild), [@vitest/coverage-v8](https://github.com/vitest-dev/vitest/tree/HEAD/packages/coverage-v8) and [vitest](https://github.com/vitest-dev/vitest/tree/HEAD/packages/vitest). These dependencies need to be updated together.


Updates `esbuild` from 0.21.5 to 0.27.2
- [Release notes](https://github.com/evanw/esbuild/releases)
- [Changelog](https://github.com/evanw/esbuild/blob/main/CHANGELOG-2024.md)
- [Commits](https://github.com/evanw/esbuild/compare/v0.21.5...v0.27.2)

Updates `@vitest/coverage-v8` from 2.1.9 to 4.0.16
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v4.0.16/packages/coverage-v8)

Updates `vitest` from 2.1.9 to 4.0.16
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v4.0.16/packages/vitest)

---
updated-dependencies:
- dependency-name: esbuild
  dependency-version: 0.27.2
  dependency-type: indirect
- dependency-name: "@vitest/coverage-v8"
  dependency-version: 4.0.16
  dependency-type: direct:development
- dependency-name: vitest
  dependency-version: 4.0.16
  dependency-type: direct:development
...

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

backend/package.json

@@ -34,10 +34,10 @@
     "@types/node": "^22.7.4",
     "@types/nodemailer": "^6.4.21",
     "@types/supertest": "^6.0.2",
-    "@vitest/coverage-v8": "^2.1.9",
+    "@vitest/coverage-v8": "^4.0.16",
     "supertest": "^7.0.0",
     "tsx": "^4.19.0",
     "typescript": "^5.5.4",
-    "vitest": "^2.1.8"
+    "vitest": "^4.0.16"
   }
 }