Fix link in CONTRIBUTING.md regarding reactions

[coliff]

Description

Fix link in CONTRIBUTING.md regarding reactions

Motivation & Context

Saves a HTTP redirect

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Checklist

• I have read the contributing guidelines
• My code follows the code style of the project (using npm run lint)
• My change introduces changes to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

Live previews

• https://deploy-preview-41927--twbs-bootstrap.netlify.app/

[Copilot]

Pull request overview

This PR updates an outdated GitHub blog URL in the CONTRIBUTING.md file to the current URL format, eliminating an HTTP redirect when users click the link about GitHub's reactions feature.

Key Changes

• Updated GitHub blog URL from the old blog.github.com format to the new github.blog format

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