fix (MToon): Workaround typing of UniformsUtils.merge

not a proper typing, might want to fix from three-ts-types side

packages/three-vrm-materials-mtoon/src/MToonMaterial.ts

@@ -446,7 +446,7 @@ export class MToonMaterial extends THREE.ShaderMaterial {
         uvAnimationRotationPhase: { value: 0.0 },
       },
       parameters.uniforms ?? {},
-    ]);
+    ]) as typeof MToonMaterial.prototype.uniforms;
 
     // == finally compile the shader program =======================================================
     this.setValues(parameters);