Add merge conflict action and update action version

[Gauvino]

Description

Added a merge conflict labeler workflow for all the PR when a merge conflict is detected so people can resolve it when commit on master branch is made. And update action version to remove the warning.

merge-conflict label need to be made before merging this PR

[openbullet]

The publish.yaml workflow is outdated and doesn't get executed anymore, I will remove it at some point. Thanks for the labeler and the action updates.