Once you’ve upgraded, try this via the UI. The best way to master the API is to perform the desired action via the UI and eavesdrop to see which calls the UI made to accomplish the action.
You’ll see that this functionality exists on the Projects page: filter by tag.
From there, it’s easy. The best way to master the API is to perform the desired action via the UI and eavesdrop to see which calls the UI made to accomplish the action.