[TASK] Update rector/rector

    composer remove --dev rector/rector
    composer require --dev rector/rector:~0.6

The update of rector brings important bugfixes and
enables the installation of the latest version of
phpstan/phpstan.

Releases: master
Resolves: #89918
Change-Id: I406aa56b19e88db23260033023e2c785425aef5e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62599
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>

composer.json

@@ -77,7 +77,7 @@
 		"codeception/codeception": "^2.5.4 || ^3",
 		"friendsofphp/php-cs-fixer": "^2.16.1",
 		"phpspec/prophecy": "^1.7.5",
-		"rector/rector": "^0.5.0",
+		"rector/rector": "~0.6",
 		"typo3/cms-styleguide": "~10.0.2",
 		"typo3/testing-framework": "~6.1.0"
 	},