[extractor/weibo] Fix visitor request

[c-basalt]

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Description of your pull request and other information

ADD DESCRIPTION HERE

Fixes #8445

Fix broken extractor due to change of guest token request.

Template

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• At least skimmed through contributing guidelines including yt-dlp coding conventions
• Searched the bugtracker for similar pull requests
• Checked the code with flake8 and ran relevant tests

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• Fix or improvement to an extractor (Make sure to add/update tests)
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• Core bug fix/improvement
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Copilot Summary

🤖 Generated by Copilot at 8494b18

Summary

🛠️🔄🗃️

Fix Weibo video extraction by updating cookie handling and data access. Modify yt_dlp/extractor/weibo.py to use the correct referer and simplify the visitor_data extraction.

We're scraping videos from Weibo, me hearties
We need to update our cookies, aye
We use the final URL as referer, on the count of three
And simplify the visitor_data, heave ho

Walkthrough

• Fix Weibo video extraction by updating visitor cookies logic (link, link)
  • Add visitor_url parameter to _update_visitor_cookies method of WeiboBaseIE class (link)
  • Use visitor_url as referer and Chrome version from user agent in requests to generate and run first-visit callback (link)
  • Simplify access to visitor_data dictionary by removing unnecessary ['data'] key (link)
  • Pass urlh.url as visitor_url to _update_visitor_cookies method in _weibo_download_json method of WeiboBaseIE class (link)
  • Use urlh.url as final URL of webpage after following redirects, which may affect first-visit callback (link)

[c-basalt]

Test cases passed on my end