Fix: broken link in the CONTRIBUTING.md.

[qiaofenlin]

Description

The previous link resulted in a 404 error. The file debugPanel.ts has been modified to ContinueGUIWebviewViewProvider.ts.

Checklist

• [ ] The base branch of this PR is dev, rather than main
• [ ] The relevant docs, if any, have been updated or created

Screenshots

[ For visual changes, include screenshots. ]

Testing

[ For new or modified features, provide step-by-step testing instructions to validate the intended behavior of the change. ]