fix linter issues

Author: GokceGK

stackit/internal/services/serverupdate/schedule/resource.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/hashicorp/terraform-plugin-framework-validators/int32validator"
 	"github.com/hashicorp/terraform-plugin-framework/resource/schema/int32planmodifier"
+
 	serverupdateUtils "github.com/stackitcloud/terraform-provider-stackit/stackit/internal/services/serverupdate/utils"
 
 	"github.com/hashicorp/terraform-plugin-framework-validators/stringvalidator"