T6235: Git update actions-label-merge-conflict version (backport #3300)

[mergify]

Change Summary

Update actions-label-merge-conflict due to Node.js 16 actions are deprecated.
https://github.com/vyos/vyos-1x/actions/runs/8658089698?pr=3291

Fixes

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: eps1lon/actions-label-merge-conflict@releases/2.x. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

eps1lon/actions-label-merge-conflict@e62d7a5

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe): Bump actions-label-merge-conflict version to 3.x

Related Task(s)

• https://vyos.dev/T6235

Related PR(s)

Component(s) name

Proposed changes

How to test

Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

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This is an automatic backport of pull request #3300 done by [Mergify](https://mergify.com).