fix: resolve duplicate logging

[binnn6]

1. Duplicate Log Entries: Each request is logged twice
   • gin.Default() already includes the Logger middleware
   • In Debug mode, gin.Logger() was added again, causing duplicate logs

Reproduction

app:
  port: 8194
  debug: True
  key: dify-sandbox
max_workers: 4
max_requests: 50
worker_timeout: 5
python_path: /usr/local/bin/python3
enable_network: True # please make sure there is no network risk in your environment
enable_preload: False # please keep it as False for security purposes
allowed_syscalls: # please leave it empty if you have no idea how seccomp works
proxy:
  socks5: ''
  http: ''
  https: ''

curl -s -X POST http://localhost:8194/v1/sandbox/run \
  -H "Content-Type: application/json" \
  -H "X-Api-Key: dify-sandbox" \
  -d '{
    "language": "python3",
    "code": "print(\"Hello from Dify Sandbox!\")\nprint(1 + 1)",
    "enable_network": false
  }'

[GIN] 2025/11/17 - 03:42:24 | 200 | 110.582µs | 172.17.0.1 | POST "/v1/sandbox/run"
[GIN] 2025/11/17 - 03:42:24 | 200 | 133.045µs | 172.17.0.1 | POST "/v1/sandbox/run"

[binnn6]

@Yeuoly Could you please review this PR?