[webhook] trigger only when merge request code is updated

Problem summary: :bar_chart:
I’m using drone CI, connected to gitlab via webhooks.
My CI webhook often triggers involontarily.

My goal :dart: :
Execute drone pipeline only when a merge request is created / updated with new code.

What I’ve done :brain:
setup gitlab webhook trigger to merge request event (cf attached screenshot)

Why it does not work :cry:
the pipeline trigger too often ! when a colleague adds a new comment into the merge request, approve it, or resolve one of its comment thread, the pipeline is triggered involuntarily.

How to achieve my goal :dart: ?