p2p/dnsdisc: using maps.Copy (#29377)

p2p/dnsdisc/client_test.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"crypto/ecdsa"
 	"errors"
+	"maps"
 	"reflect"
 	"testing"
 	"time"
@@ -453,9 +454,7 @@ func (mr mapResolver) clear() {
 }
 
 func (mr mapResolver) add(m map[string]string) {
-	for k, v := range m {
+	maps.Copy(mr, m)
-		mr[k] = v
-	}
 }
 
 func (mr mapResolver) LookupTXT(ctx context.Context, name string) ([]string, error) {