fix(admin-ui): Fix updating variant tax category

Fixes #2336

packages/admin-ui/src/lib/catalog/src/components/product-variant-detail/product-variant-detail.component.ts

@@ -207,7 +207,6 @@ export class ProductVariantDetailComponent
             .pipe(
                 take(1),
                 mergeMap(([variant, languageCode]) => {
-                    const formValue = this.detailForm.value;
                     const input = pick(
                         this.getUpdatedVariant(
                             variant,
@@ -400,6 +399,7 @@ export class ProductVariantDetailComponent
             assetIds: this.assetChanges.assets?.map(a => a.id),
             featuredAssetId: this.assetChanges.featuredAsset?.id,
             facetValueIds: variantFormGroup.value.facetValueIds,
+            taxCategoryId: variantFormGroup.value.taxCategoryId,
         } as UpdateProductVariantInput | CreateProductVariantInput;
     }
 }