[Help needed] stri_datetime_parse crash on M1mac

https://www.stats.ox.ac.uk/pub/bdr/M1mac/stringi.out

reports:

```
* checking examples ...sh: line 1: 4716 Abort trap: 6 LANGUAGE=en _R_CHECK_INTERNALS2_=1 '/Users/ripley/R/R-devel/bin/R' --vanilla > 'stringi-Ex.Rout' 2>&1 < 'stringi-Ex.R'
ERROR
Running examples in ‘stringi-Ex.R’ failed
The error most likely occurred in:

> ### Name: stri_datetime_format
> ### Title: Date and Time Formatting and Parsing
> ### Aliases: stri_datetime_format stri_datetime_parse
>
> ### ** Examples
>
> x <- '2015-02-28'
> stri_datetime_parse(x, 'yyyy-MM-dd') # try '2015-02-29'
```

Can anyone reproduce this and suggest a fix? I can't reproduce the above and the crash report is not verbose enough. :/

Start with the linked stringi.out report and the stringi-Ex.R example for stri_datetime_parse, focusing on the stri_datetime_format/stri_datetime_parse case shown. Reproduce the abort on an M1 Mac with the package's example checks, then use the crash details to identify and validate a fix.

Written by the indexing model from the issue text.