build(deps): bump openai

Bumps the production group in /services/discord-gateway with 1 update: [openai](https://github.com/openai/openai-node).


Updates `openai` from 7.15.0 to 7.18.0
- [Release notes](https://github.com/openai/openai-node/releases)
- [Changelog](https://github.com/openai/openai-node/blob/main/CHANGELOG.md)
- [Commits](https://github.com/openai/openai-node/compare/v7.15.0...v7.18.0)

---
updated-dependencies:
- dependency-name: openai
  dependency-version: 7.18.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: production
...

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

services/discord-gateway/package.json

@@ -34,7 +34,7 @@
     "ioredis": "^6.0.0",
     "libsodium-wrappers": "^0.8.4",
     "lru-cache": "^11.5.1",
-    "openai": "^7.15.0",
+    "openai": "^7.18.0",
     "opusscript": "^0.1.1",
     "p-limit": "^7.3.2",
     "p-retry": "^8.0.1",