[HANDS-ON BUG] Unable to download files

**Describe the bug**
Whenever I try to download a file I get a 404

**To Reproduce**
```
url = "https://agents-course-unit4-scoring.hf.space"
requests.get(f"{url}/files/cca530fc-4052-43b2-b130-b30968d8aa44")
# This task should contains a .png
# {'task_id': 'cca530fc-4052-43b2-b130-b30968d8aa44', 'question': "Review the chess position provided in the image. It is black's turn. Provide the correct next move for black which guarantees a win. Please provide your response in algebraic notation.", 'Level': '1', 'file_name': 'cca530fc-4052-43b2-b130-b30968d8aa44.png'}
```

[https://agents-course-unit4-scoring.hf.space/files/cca530fc-4052-43b2-b130-b30968d8aa44](url)

**Additional context**
The endpoint /questions is working, it's just this one that seems missing