Update composer.json

[lloc]

I followed the install instructions for the WordCamp multisite during the contributor day at WCEU 2024. I faced an error when I tried to get a list of the websites for my "hosts" file. Looking into the composer.json I realized that some jobs were not executed. Running composer update separately solved the problem.

My proposal is that:

post-update-cmd and post-install-cmd should share the same jobs.

@2ndkauboy @renintw @pkevan