MeshGouraudMaterial: Deprecate module. (#30314)

Author: Mugen87

examples/jsm/materials/MeshGouraudMaterial.js

@@ -319,6 +319,8 @@ class MeshGouraudMaterial extends ShaderMaterial {
 
 		super();
 
+		console.warn( 'THREE.MeshGouraudMaterial: MeshGouraudMaterial has been deprecated and will be removed with r183. Use THREE.MeshLambertMaterial instead.' ); // @deprecated r173
+
 		this.isMeshGouraudMaterial = true;
 
 		this.type = 'MeshGouraudMaterial';