[BUG]: trouble with cyrillic encoding in emayili::render

[selesnow]

Description of the bug

I have Rmd file with cyrillic (russian language) text. When i try rending (emayili::render()) and send it i get next:

My rending code:

library(emayili)
library(stringr)
library(rmarkdown)

Sys.setlocale(locale = 'russian')

rmarkdown::render(here::here('rmd', 'fb_spend_limit_checker.rmd'), encoding = 'CP1251')

email <- envelope() %>% 
  emayili::render(here::here('rmd', 'fb_spend_limit_checker.html')) %>% 
  from("Netpeak Analytics Dept. <bi@netpeak.net>") %>% 
  to(c("a.seleznev@netpeak.group"))  %>% #, "d.skliar@netpeak.net")) %>% 
  subject("Дайджест: Контроль лимита расходов в Facebook аккаунтах за {{format(Sys.Date(), '%d.%m.%Y')}}", interpolate = T)
  
# send mail
smtp <- gmail(Sys.getenv('DEPT_EMAIL'), Sys.getenv('DEPT_EMAIL_PWD'))
smtp(email)

But i can fix it over iconv:

library(emayili)
library(stringr)
library(rmarkdown)

Sys.setlocale(locale = 'russian')

rmarkdown::render(here::here('rmd', 'fb_spend_limit_checker.rmd'), encoding = 'CP1251')

email <- envelope() %>% 
  emayili::render(here::here('rmd', 'fb_spend_limit_checker.html')) %>% 
  from("Netpeak Analytics Dept. <bi@netpeak.net>") %>% 
  to(c("a.seleznev@netpeak.group"))  %>% #, "d.skliar@netpeak.net")) %>% 
  subject("Дайджест: Контроль лимита расходов в Facebook аккаунтах за {{format(Sys.Date(), '%d.%m.%Y')}}", interpolate = T)
  
# -------------------------------------------------------------------------->
# -------------------------------------------------------------------------->
# fix encoding
email$parts[[1]]$content <- iconv(email$parts[[1]]$content, from = 'UTF-8', to = '1251') %>% iconv(from = 'UTF-8', to = '1251')
# ---------------------------------------------------------------------------
# ---------------------------------------------------------------------------

# send mail
smtp <- gmail(Sys.getenv('DEPT_EMAIL'), Sys.getenv('DEPT_EMAIL_PWD'))
smtp(email)

My session info

> sessionInfo()
R version 4.2.1 (2022-06-23 ucrt)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows Server x64 (build 14393)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=Russian_Russia.1251           LC_MONETARY=English_United States.1252 LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] rmarkdown_2.16 stringr_1.4.1  emayili_0.7.13

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.9       pillar_1.8.1     compiler_4.2.1   base64enc_0.1-3  tools_4.2.1      digest_0.6.29    evaluate_0.16    lifecycle_1.0.2  tibble_3.1.8    
[10] pkgconfig_2.0.3  rlang_1.0.5      cli_3.4.0        DBI_1.1.3        rstudioapi_0.14  commonmark_1.8.0 curl_4.3.2       xfun_0.32        fastmap_1.1.0   
[19] dplyr_1.0.10     httr_1.4.4       knitr_1.40       xml2_1.3.3       generics_0.1.3   vctrs_0.4.1      triebeard_0.3.0  rprojroot_2.0.3  tidyselect_1.1.2
[28] glue_1.6.2       here_1.0.1       R6_2.5.1         fansi_1.0.3      purrr_0.3.4      tidyr_1.2.1      logger_0.2.2     magrittr_2.0.3   urltools_1.7.3  
[37] htmltools_0.5.3  assertthat_0.2.1 rvest_1.0.3      mime_0.12        utf8_1.2.2       stringi_1.7.8   

Steps To Reproduce

Part of Rmd filr

---
title: "Дайджест контроля лимита трат в Facebook"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Дайджест контроля лимита трат в Facebook}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)

Этот дайджест позволяет контролировать установленные лимиты затрат в рекламных аккаунтах Facebook, по проуктам услуги "Пополнение Facebook".

library(kableExtra)
library(tidyr)

df <- data.frame('колонка 1' = c(1,2,3), 'колонка 2' = c(4,5,6))

kbl(df)

Rending code

library(emayili)
library(stringr)
library(rmarkdown)

Sys.setlocale(locale = 'russian')

rmarkdown::render(here::here('rmd', 'fb_spend_limit_checker.rmd'), encoding = 'CP1251')

email <- envelope() %>%
emayili::render(here::here('rmd', 'fb_spend_limit_checker.html')) %>%
from("Netpeak Analytics Dept. bi@netpeak.net") %>%
to(c("a.seleznev@netpeak.group")) %>% #, "d.skliar@netpeak.net")) %>%
subject("Дайджест: Контроль лимита расходов в Facebook аккаунтах за {{format(Sys.Date(), '%d.%m.%Y')}}", interpolate = T)

send mail

smtp <- gmail(Sys.getenv('DEPT_EMAIL'), Sys.getenv('DEPT_EMAIL_PWD'))
smtp(email)

### Additional Information

> sessionInfo()
R version 4.2.1 (2022-06-23 ucrt)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows Server x64 (build 14393)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=Russian_Russia.1251           LC_MONETARY=English_United States.1252 LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] rmarkdown_2.16 stringr_1.4.1  emayili_0.7.13

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.9       pillar_1.8.1     compiler_4.2.1   base64enc_0.1-3  tools_4.2.1      digest_0.6.29    evaluate_0.16    lifecycle_1.0.2  tibble_3.1.8    
[10] pkgconfig_2.0.3  rlang_1.0.5      cli_3.4.0        DBI_1.1.3        rstudioapi_0.14  commonmark_1.8.0 curl_4.3.2       xfun_0.32        fastmap_1.1.0   
[19] dplyr_1.0.10     httr_1.4.4       knitr_1.40       xml2_1.3.3       generics_0.1.3   vctrs_0.4.1      triebeard_0.3.0  rprojroot_2.0.3  tidyselect_1.1.2
[28] glue_1.6.2       here_1.0.1       R6_2.5.1         fansi_1.0.3      purrr_0.3.4      tidyr_1.2.1      logger_0.2.2     magrittr_2.0.3   urltools_1.7.3  
[37] htmltools_0.5.3  assertthat_0.2.1 rvest_1.0.3      mime_0.12        utf8_1.2.2       stringi_1.7.8