It seems that around 90% of developers are men[1]. Therefore, using a binomial distribution, if 6 developers were picked at random, the chance that all of them would be women (or other non men gender) is 0.0001%. (Interestingly, there is a 53% chance that all 6 of would be men).
The reason for such unlikely occurrence is that most likely, as the parent mentioned, Apple wanted to feature women developers for International Women's Day.
[1] https://www.statista.com/statistics/1126823/worldwide-develo...
I'm glad Apple are showcasing the diversity of their workforce (I raised three daughters of my own, wish they would have shown an interest in programming, not really) but I worry that there is a danger of backlash for going too far.