chore: remove refs to deprecated io/ioutil

Signed-off-by: guoguangwu <guoguangwug@gmail.com>

server/resolvers/test_endpoint.go

@@ -5,7 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"time"
 
@@ -90,7 +90,7 @@ func TestEndpointResolver(ctx context.Context, params model.TestEndpointRequest)
 	}
 	defer resp.Body.Close()
 
-	body, err := ioutil.ReadAll(resp.Body)
+	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		log.Debug("error reading response: ", err)
 		return nil, err