Add Django 6.1

[adamchainz]

Currently in alpha: https://www.djangoproject.com/weblog/2026/may/20/django-61-alpha-1-released/

…which means that its docs pages are up: https://docs.djangoproject.com/en/6.1/

If you're updating existing documentation to its latest version, please ensure that you have:

• Updated the versions and releases in the scraper file
• Ensured the license is up-to-date
• Ensured the icons and the SOURCE file in public/icons/your_scraper_name/ are up-to-date if the documentation has a custom icon
• Ensured self.links contains up-to-date urls if self.links is defined
• Tested the changes locally to ensure:
  • The scraper still works without errors
  • The scraped documentation still looks consistent with the rest of DevDocs
  • The categorization of entries is still good

(Copying from my previous Django 6.0 PR, #2580, and the previous versions before it.)

[simon04]

Thank you!