Update I3DMLoader.d.ts

src/three/I3DMLoader.d.ts

@@ -1,6 +1,7 @@
 import { I3DMBaseResult } from '../base/I3DMLoaderBase';
 import { FeatureTable, BatchTable } from '../utilities/FeatureTable';
 import { GLTF } from 'three/examples/jsm/loaders/GLTFLoader';
+import { Group, LoadingManager } from 'three';
 
 interface I3DMScene extends Group {