Upgrade Status tests fail on PHP 7.4 and PHP 8.0 due to lack of rules.neon used from phpstan-drupal

Ok this is strange. Tested on PHP 8.1 and this deprecation is not reported anymore for the test module:

Configuration entity must define a `config_export` key. See https://www.drupal.org/node/2481909

The phpstan-drupal rule is defined at phpstan-drupal/src/Rules/Deprecations/ConfigEntityConfigExportRule.php.

What seems to be the case is that a minimum of PHP 7.4 is required by phpstan-drupal 1.1.5 and up. Earlier versions of phpstan-drupal still supported PHP down to PHP 7.1, so 1.1.4 is used on the PHP 7.3 environments. Verified on https://dispatcher.drupalci.org/job/drupal_contrib/601601/console: Installing mglaman/phpstan-drupal (1.1.4): Extracting archive.

In other words, the PHP 7.3 environment is testing a quite old version of phpsta-drupal (1.1.4 release was 2021-12-29).

On the other hand, the history of https://github.com/mglaman/phpstan-drupal/commits/main/src/Rules/Depreca... does not indicate any change that would cause it not to run or be "fixed" to be more strict than what it was before.

Started failing between April 7 and April 14, so between Installing mglaman/phpstan-drupal (1.1.15) and Installing mglaman/phpstan-drupal (1.1.16).

So the difference turns out that 1.1.16 introduced a new rules.neon file, we need to include that too.

So this solved PHP 7.4 and 8.0. The 8.1 fail is due to Guzzle, see #3274645: Deprecated function: Return type of GuzzleHttp\Cookie\CookieJar when running Upgrade Status on PHP 8.1.