fix compute_seats()

[TuQmano]

• add electoral threshold (3% of districts electorate)

[TuQmano]

Modify workflow like this. Need to fix #9 first

data <- data %>% 
    dplyr::mutate(type = dplyr::case_when(
      year %in% presi_years ~ "presidentials",
      year %in% midterm_years ~ "midterms"
    )) %>% 
    dplyr::left_join(seats_election, by = c("codprov", "type")) %>% 
    dplyr::filter(!stringr::str_detect(listas, "\\D"))%>% 
    dplyr::group_by(codprov, name_prov) %>%  ############################ ADD VOTES Threshold
    dplyr::filter(electores*.003 < votos)