docs: bump yard to 0.9.39

[GunniBusch]

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In #21999 I forgot to also bump yard (to 0.9.39) in docs/Gemfile.lock, since that is used to publish the docs. I only updated Library/Homebrew/Gemfile.lock in the previous pr.

I also removed the yard fork from the .lock and Gemfile as 0.9.39 supports ruby 4.

[Copilot]

Pull request overview

Updates the documentation site’s Bundler dependencies to use the upstream yard gem (v0.9.39) instead of a temporary GitHub fork, aligning the docs build dependencies with the main Homebrew Ruby bundle after the Ruby 4 compatibility fix landed upstream.

Changes:

• Remove the yard GitHub fork pin from docs/Gemfile.
• Update docs/Gemfile.lock to pull yard (0.9.39) from RubyGems and drop the prior GIT source block.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
docs/Gemfile.lock	Removes the forked yard Git source and locks to yard 0.9.39 from RubyGems for docs publishing.
docs/Gemfile	Switches yard dependency back to the standard RubyGems source (no fork/ref).

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[p-linnane]

Thanks!