T7878: Using mergify rule to handle conflict checks for private repo - updated label

[kumvijaya]

Change summary

Mergify Conflict Label Fix

Mergify automatically adds and removes a label named conflicts (plural) when pull requests have merge conflicts.
Our existing configuration used conflict (singular), which caused Mergify to fail to toggle the label properly.

Problem

• Mergify’s default behavior expects the label name conflicts.
• Our rule defined the label as conflict.
• As a result, the label wasn’t removed when merge conflicts were resolved.

Resolution

Updated the rule to use the correct label name:

actions:
  label:
    toggle:
      - conflicts

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):

Related Task(s)

https://vyos.dev/T7878

Related PR(s)

Checklist:

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

[github-actions]

👍
No issues in PR Title / Commit Title

[sever-sever]

Fix label