build(deps-dev): bump @nestjs/testing from 10.4.1 to 10.4.15

Bumps [@nestjs/testing](https://github.com/nestjs/nest/tree/HEAD/packages/testing) from 10.4.1 to 10.4.15.
- [Release notes](https://github.com/nestjs/nest/releases)
- [Commits](https://github.com/nestjs/nest/commits/v10.4.15/packages/testing)

---
updated-dependencies:
- dependency-name: "@nestjs/testing"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>