message: Replace `string_format` with `std::to_string`
  It doesn't read quite as nice, but `string_format` will be removed.
diff: @@ -227,7 +227,7 @@ void FactoryProduction::update()
  };
  auto position = rect().startPoint() + NAS2D::Vector{constants::MARGIN * 2 + static_cast<int>(mProductGrid.width()), 25};
  - drawTitleText(position, "Turns Completed:", string_format("%i of %i", mFactory->productionTurnsCompleted(), mProductCost.turnsToBuild()));
  + drawTitleText(position, "Turns Completed:", std::to_string(mFactory->productionTurnsCompleted()) + " of " + std::to_string(mProductCost.turnsToBuild()));
  position.y() += 20;
  drawTitleText(position, "Common Metals:", std::to_string(mProductCost.commonMetals() * mProductCost.turnsToBuild()));
  