Fix invalidating project cache on link/unlink search widget. (#790)

Co-authored-by: wlorenzetti <[email protected]>

g3w-admin/qdjango/views/projects.py

@@ -800,6 +800,10 @@ def linkUnlinkWidget(self, link=True):
         else:
             self.widget.layers.remove(self.layer)
 
+        # Invalidate project cache
+        self.layer.project.invalidate_cache()
+
+
 
 class QdjangoLayerDetailView(G3WRequestViewMixin, DetailView):
     """Detail view for qdjango layer object"""