fix(data-loader): restore Apollo Server v4 to resolve CI break from dependency bump

[Copilot]

The dependency-bump PR pulled @apollo/server to v5 in packages/data-loader, which is incompatible with the current Nest Apollo integration used by the package. CI failed because the v4 integration subpath expected by @nestjs/apollo is not exported by Apollo Server v5.

• Scope

  • Targets only the CI regression introduced by the dependency update in packages/data-loader.

• Dependency compatibility change

  • Reverted @apollo/server in packages/data-loader/package.json from ^5.4.0 to ^4.11.3.
  • Keeps the package aligned with the currently used @nestjs/apollo integration surface.

• Lockfile alignment

  • Updated yarn.lock to reflect the v4 Apollo graph and remove the incompatible v5 resolution path.

// packages/data-loader/package.json
{
  "devDependencies": {
    "@apollo/server": "^4.11.3"
  }
}

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