Don't translate termcodes twice on input

`getcharstr()` already returns raw internal termcodes, it is wrong to
call nvim_replace_termcodes on its result.

This effectively reverts PR #273

refs: neovim/neovim#29034
fixes: #325

lua/nvim-surround/input.lua

@@ -9,8 +9,7 @@ M.get_char = function()
     if not ok or char == "\27" then
         return nil
     end
-    -- Call this function, because config.translate_opts() does too
-    return vim.api.nvim_replace_termcodes(char, true, true, true)
+    return char
 end
 
 -- Gets a string input from the user.