Fix import groups in kubernetes/planpreview/plugin.go (#6225)

Author: Warashi

pkg/app/pipedv1/plugin/kubernetes/planpreview/plugin.go

@@ -18,12 +18,12 @@ import (
 	"context"
 	"fmt"
 
+	sdk "github.com/pipe-cd/piped-plugin-sdk-go"
+	"github.com/pipe-cd/piped-plugin-sdk-go/diff"
+
 	kubeconfig "github.com/pipe-cd/pipecd/pkg/app/pipedv1/plugin/kubernetes/config"
 	"github.com/pipe-cd/pipecd/pkg/app/pipedv1/plugin/kubernetes/provider"
 	"github.com/pipe-cd/pipecd/pkg/app/pipedv1/plugin/kubernetes/toolregistry"
-	"github.com/pipe-cd/piped-plugin-sdk-go/diff"
-
-	sdk "github.com/pipe-cd/piped-plugin-sdk-go"
 )
 
 var (