mitigate race against server readiness in test

Co-authored-by: Romain <rtribotte@users.noreply.github.com>

pkg/server/server_entrypoint_tcp_http3_test.go

@@ -6,6 +6,7 @@ import (
 	"crypto/tls"
 	"net/http"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -113,6 +114,9 @@ func TestHTTP3AdvertisedPort(t *testing.T) {
 	})
 	require.NoError(t, err)
 
+	// We are racing with the http3Server readiness happening in the goroutine starting the entrypoint
+	time.Sleep(time.Second)
+
 	request, err := http.NewRequest(http.MethodGet, "https://127.0.0.1:8090", nil)
 	require.NoError(t, err)