[Bug]: Demo project failed to start

### What happened?

I followed the documentation to test the demo-ui project, but an error occurred:

file_name: static_file_serving.py
row: 178

### Relevant log output

```shell
raise Exception("Unexpected CSP violation:", violated_directive, report)
Exception: ('Unexpected CSP violation:', 'font-src', {'csp-report': {'document-uri': 'http://localhost:12000/', 'referrer': '', 'violated-directive': 'font-src', 'effective-directive
': 'font-src', 'original-policy': "default-src 'self'; font-src 'self' fonts.gstatic.com data:; frame-src *; img-src 'self' data: https: http: blob:; media-src 'self' data: https: bl
ob:; style-src 'self' 'unsafe-inline' fonts.googleapis.com; script-src 'self' 'nonce-GP0iNdjiWzq2TA1q0JyXRQ' https://cdn.jsdelivr.net; trusted-types angular angular#unsafe-bypass lit
-html highlight.js; require-trusted-types-for 'script'; report-uri /__csp__; frame-ancestors 'self'", 'disposition': 'enforce', 'blocked-uri': 'http://at.alicdn.com/t/font_1334179_yeeyzhmgwya.ttf?t=1564991718045', 'line-number': 19, 'source-file': 'http://localhost:12000/', 'status-code': 200, 'script-sample': ''}})
```

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

The error is in static_file_serving.py at line 178, where a CSP violation for font-src is raised. Examine the Content Security Policy configuration and the blocked font URI 'http://at.alicdn.com'. Check if the font source needs to be added to the policy or if the request should be allowed. Run the demo-ui project locally to reproduce the issue and test the fix.

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