PortfolioTesteR example failures after frollapply modification

[tdhock]

Affected package

https://github.com/AlbertoPallotta/PortfolioTesteR

Problem description

example(calc_rolling_volatility)

Failing check output

* checking examples ... ERROR
Running examples in 'PortfolioTesteR-Ex.R' failed
The error most likely occurred in:

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: calc_rolling_volatility
> ### Title: Calculate Rolling Volatility
> ### Aliases: calc_rolling_volatility
> 
> ### ** Examples
> 
> data("sample_prices_weekly")
> # Standard deviation volatility
> vol <- calc_rolling_volatility(sample_prices_weekly, lookback = 20)
> # Range-based volatility
> vol_range <- calc_rolling_volatility(sample_prices_weekly, lookback = 20, method = "range")
Error in frollapply(get(col), n = lookback, FUN = function(x) { : 
  'n' is deprecated in frollapply, use 'N' instead
Calls: calc_rolling_volatility ... eval -> frollapply -> stopf -> raise_condition -> signal

First bad commit/PR

Rdatatable#7530

Minimal reproducible example

Additional context

TODO mention