fix: MToon, Fix normal mapping when other textures are not specified

See: #1384 (comment)

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

@@ -606,6 +606,7 @@ export class MToonMaterial extends THREE.ShaderMaterial {
     const useUvInVert = this.outlineWidthMultiplyTexture !== null;
     const useUvInFrag =
       this.map !== null ||
+      this.normalMap !== null ||
       this.emissiveMap !== null ||
       this.shadeMultiplyTexture !== null ||
       this.shadingShiftTexture !== null ||