[meta] Release preparation steps for 10.2.0

@longwave and I agreed that we would like to get #3343634: Add "json" as core data type to Schema and Database API in before beta (allow it in between alpha and beta) if it's ready before beta, so adding it to the issue summary's target issues list.

What is the drop-dead date for the JSON data types issue to be included?

10.2.0-beta1 is due next week and feature and API additions have to land before then in order to make it into 10.2.0.

OK thanks... Seems very tight to get it from where it is to RTBC by then, but we'll see how far I can get it in the next few days.

Added the docs critical for attribute plugin discovery.

Adding a critical regression.

Another critical.

Added another regression, added a note about Symfony 6.4 final release, moved completed issues to done.

Adding missing PhpRequirements child.