Fix GitHub Copilot CLA allowlist to prevent false CLA requirement

[Copilot]

This PR fixes an issue where GitHub Copilot was incorrectly being required to sign the CLA despite being added to the allowlist.

Problem

The CLA workflow had copilot in the allowlist, but GitHub Copilot appears with different username formats when making contributions (such as github-copilot[bot] or copilot[bot]). This caused the CLA Assistant to incorrectly flag Copilot contributions as requiring CLA signature, as shown in the issue screenshot where @copilot was marked with a red X and required to sign the CLA.

Solution

Updated the CLA workflow allowlist to include the correct GitHub Copilot bot formats:

• Added github-copilot[bot] (most common GitHub Copilot format)
• Added copilot[bot] (alternative GitHub Copilot format)
• Kept existing copilot entry for backward compatibility
• Reformatted the allowlist as multi-line YAML for better readability

The allowlist now properly covers all possible GitHub Copilot username variations while maintaining compatibility with existing entries.

Changes

# Before
allowlist: github-actions[bot],dependabot-preview[bot],insights-engineering-bot,dependabot[bot],copilot

# After  
allowlist: >-
  github-actions[bot],
  dependabot-preview[bot],
  insights-engineering-bot,
  dependabot[bot],
  copilot,
  github-copilot[bot],
  copilot[bot]

Fixes #30.

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[Copilot]

@m7pr 👋 This repository doesn't have Copilot instructions. With Copilot instructions, I can understand the repository better, work faster and produce higher quality PRs.

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[github-actions]

🎉 Thank you for your contribution! Before this PR can be accepted, we require that you all read and agree to our Contributor License Agreement.
You can digitally sign the CLA by posting a comment on this Pull Request in the format shown below. This agreement will apply to this PR as well as all future contributions on this repository.

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I have read the CLA Document and I hereby sign the CLA

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1 out of 2 committers have signed the CLA.
✅ (m7pr)[https://github.com/m7pr]
❌ @Copilot
_{You can retrigger this bot by commenting recheck in this Pull Request. Posted by the CLA Assistant Lite bot.}

[m7pr]

I have read the CLA Document and I hereby sign the CLA