gitlab_group_label requires replacement when name is modified

Current behaviour

A modification to the name of a label requires a replacement.

Expected behaviour

A modification to the name of a label should perform an update in-place.

Why?

• GitLab allows labels' names to be updated via the UI without modifying the label ID.
• Destroying a label and creating a new one will remove the existing label from issues etc and the replacement will not be added to these issues.