Using GPT5 models results in error

Tested with `gpt-5-nano` and `gpt-5-mini`. Error below:

```
2025-08-23 08:53:30.553 [error] Error: An unexpected error occurred
	at .../.vscode/extensions/sitoi.ai-commit-0.1.1/dist/extension.js:2:150449
	at process.processTicksAndRejections (node:internal/process/task_queues:105:5) extension.ai-commit {"value":"sitoi.ai-commit","_lower":"sitoi.ai-commit"}
```