fix(mise): upgrade helm to 3.21 to fix helm testdata generation - #25520

// runHelmTemplate runs helm template on the given chart with the given values and
// returns the raw output.
func runHelmTemplate(t testing.TB, helmPath, chartDir, valuesFilePath, namespace string) (string, error) {
	// Ensure that valuesFilePath exists
	if _, err := os.Stat(valuesFilePath); err != nil {
		return "", xerrors.Errorf("values file %q does not exist: %w", valuesFilePath, err)
	}

	cmd := exec.Command(helmPath, "template", chartDir, "-f", valuesFilePath, "--namespace", namespace)
	t.Logf("exec command: %v", cmd.Args)
	out, err := cmd.CombinedOutput()
	return string(out), err
}