Increase Drupal::MINIMUM_PHP to 8.0.2

Problem/Motivation

In #3252088: Increase Drupal::MINIMUM_PHP to 8.0.0 we bumped Drupal 10.0.x to PHP 8.0.0.

We have since discovered some Symfony components require PHP 8.0.2 or above:

$ composer why-not symfony/event-dispatcher-contracts 3
symfony/event-dispatcher-contracts  v3.0.0  requires  php (>=8.0.2 but 8.0.0 is installed) 

Steps to reproduce

Proposed resolution

Bump MINIMUM_PHP and related constants (e.g. in composer.json) to 8.0.2.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet

Drupal 10's minimum PHP version requirement is PHP 8.0.2. It will not be possible to run Drupal 10 on PHP 7 or earlier. However, there is a possibility that before Drupal 10's release, the PHP requirement will be raised again to PHP 8.1. See #3173787: [policy] Require PHP 8.1 for Drupal 10.0 if a dependency does, otherwise require PHP 8.0. (up from 7.3 in Drupal 9) for ongoing discussion.