[TS] Allow array of Materials in InstancedMesh generics declaration - Fixes #19500

src/objects/InstancedMesh.d.ts

@@ -7,7 +7,7 @@ import { Matrix4 } from './../math/Matrix4';
 
 export class InstancedMesh <
 	TGeometry extends Geometry | BufferGeometry = Geometry | BufferGeometry,
-	TMaterial extends Material = Material
+	TMaterial extends Material | Material[] = Material | Material[]
 > extends Mesh {
 
 	constructor(