Fix broken 404 page

[AlgoFoe]

Description

What is this PR

• Bug fix
• Addition of a new feature
• Other

Why is this PR needed?

• Versioned documentation URLs were not resolving to the custom 404 page, resulting in broken 404 behavior.

What does this PR do?

• Fixes the notfound-page configuration by setting notfound_urls_prefix to the correct value for gh-pages.

References

• Fixes Broken 404 page #784

How has this PR been tested?

• Built the docs locally using make html and verified that the custom 404.html page is generated.

Is this a breaking change?

• No.

Does this PR require an update to the documentation?

• No.

Checklist:

• The code has been tested locally
• Tests have been added to cover all new functionality
• The documentation has been updated to reflect any changes
• The code has been formatted with pre-commit

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (b3f5a9c) to head (2992020).

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #785   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           34        34           
  Lines         2111      2111           
=========================================
  Hits          2111      2111           

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[AlgoFoe]

Hi @lochhh! The CI failure may be due to a linkcheck error, I am seeing a 403 for this link during make linkcheck and looks like an external link issue.