message: integration_tests: fix casting warning on Windows
diff: @@ -59,7 +59,7 @@ void takeoff_and_hover_at_altitude(float altitude_m)
  action_ret = device.action().takeoff();
  EXPECT_EQ(action_ret, Action::Result::SUCCESS);
  // We wait 1.5s / m plus a margin of 3s.
  - const int wait_time_s = altitude_m * 1.5f + 3.0f;
  + const int wait_time_s = static_cast<int>(altitude_m * 1.5f + 3.0f);
  std::this_thread::sleep_for(std::chrono::seconds(wait_time_s));
  