ci: change matrix.node to matrix.node_version

[wolfy1339]

All the other Js Octokit repos use node_version, therefore this workflow should be normalized to use the same names

Resolves #ISSUE_NUMBER

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Behavior

Before the change?

• This repo was using node as the matrix name in the test.yml workflow

After the change?

• Normalize the name to correspond to the other Octokit repos

Other information

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Additional info

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Added the appropriate label for the given change

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• Yes (Please add the Type: Breaking change label)
• No

If Yes, what's the impact:

• N/A

Pull request type

Please add the corresponding label for change this PR introduces:

• Dependencies/code cleanup: Type: Maintenance

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[github-actions]

🎉 This PR is included in version 11.1.0 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

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