Bump LayerView API version to 3

It does not use any setting API so it is safe

plugins/LayerView/__init__.py

@@ -14,7 +14,7 @@ def getMetaData():
             "author": "Ultimaker",
             "version": "1.0",
             "description": catalog.i18nc("@info:whatsthis", "Provides the Layer view."),
-            "api": 2
+            "api": 3
         },
         "view": {
             "name": catalog.i18nc("@item:inlistbox", "Layers"),