HTML summary row styling fix

[rich-iannone]

A bug in the summary_row_tags() util function (in utils_render_html.R) can occasionally result in styles not being applied to certain summary rows. Issue #752 has an example where this is the case, and the first summary row does not have styling applied:

library(gt)
library(tidyverse)

tibble(
  div_num=c("630", "641", "643", "643", "646", "647"), 
  group_num=c("01","02","09","10","05","02"), 
  count=as.integer(c(1,1,1,1,8,2))
) %>% 
  group_by(div_num) %>% 
  gt(rowname_col = 'group_num') %>% 
  summary_rows(
    groups = TRUE,
    columns = vars(count),
    fns = list(`Division total: `="sum"),
    formatter = fmt_number,
    decimals = 0
  ) %>% tab_style(
    style = list(
      cell_text(
        weight = "bold",
        size = px(12)
      ),
      cell_fill("red")
    ),
    locations = cells_summary()
  ) 

The problem is traced to the statement in the summary_row_tags() function that resolves a decimal-based row number (rownum) to a whole number with ceiling((rownum %% 1) * 100). To fix the bug, the round() function should be used in place of ceiling().

Fixes: #752