message: fix suspicious string literal reported by clang-tidy
diff: @@ -3118,7 +3118,7 @@ static void test_SimpleRollAdopter() {
  std::vector<double> d3 = { 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 };
  std::vector<double> d4 = { 22, 23, 24, 25, 26, 27 };
  std::vector<std::string> s1 =
  - { "11", "22", "33", "aa", "bb", "cc", "dd" "tt", "uu", "ii", "88" };
  + { "11", "22", "33", "aa", "bb", "cc", "dd", "tt", "uu", "ii", "88" };
  MyDataFrame df;
  df.load_data(std::move(idx),
  @@ -3198,7 +3198,7 @@ static void test_ExponentialRollAdopter() {
  std::vector<double> d3 = { 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 };
  std::vector<double> d4 = { 22, 23, 24, 25, 26, 27 };
  std::vector<std::string> s1 =
  - { "11", "22", "33", "aa", "bb", "cc", "dd" "tt", "uu", "ii", "88" };
  + { "11", "22", "33", "aa", "bb", "cc", "dd", "tt", "uu", "ii", "88" };
  MyDataFrame df;
  df.load_data(std::move(idx),
  @@ -3289,7 +3289,7 @@ static void test_ExponentiallyWeightedMeanVisitor() {
  std::vector<double> d3 = { 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 };
  std::vector<double> d4 = { 22, 23, 24, 25, 26, 27 };
  std::vector<std::string> s1 =
  - { "11", "22", "33", "aa", "bb", "cc", "dd" "tt", "uu", "ii", "88" };
  + { "11", "22", "33", "aa", "bb", "cc", "dd", "tt", "uu", "ii", "88" };
  MyDataFrame df;
  df.load_data(std::move(idx),
  