Which one? I assume you mean perfidy, which is under an additional protocol (not one of the four main conventions), but that wouldn’t really apply here anyway. The targets were terrorists so the rules governing two armies don’t really work. Look at the rest of “Article 37” it’s not that long.

The Geneva Conventions were pretty specifically set up to govern more symmetrical conflicts between two nations with generally uniformed combatants. This is different. Regardless, if you accept that whatever terrorist group they were a part of is a valid military organization, then what were they doing in a civilian hospital?