eigen@3 3.4.1 (new formula)

[cho-m]

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Simplifying #246477 by adding eigen@3 first to help with migration.

[Copilot]

Pull Request Overview

This PR introduces a versioned formula eigen@3 to pin Eigen to version 3.x and updates the autodiff formula to depend on this versioned formula instead of the main eigen formula.

Key changes:

• Created eigen@3.rb as a versioned formula for Eigen 3.x series
• Updated autodiff to use eigen@3 dependency
• Bumped autodiff revision to trigger rebuild

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
Formula/e/eigen@3.rb	New versioned formula for Eigen 3.x with keg_only status and version-specific livecheck
Formula/a/autodiff.rb	Updated to depend on eigen@3 instead of eigen, with revision bump and test references updated

[github-actions]

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