Use correct Extension class per Symfony deprecation #508

Job	Run time
Coding style	17s
PHPUnit (PHP 7.4, Symfony 5.4.* + highest deps, ES 7.11.0)	1m 18s
PHPStan (PHP 7.4, Symfony 5.4.* + highest deps)	2m 49s
PHPUnit (PHP 8.1, Symfony 5.4.* + highest deps, ES 7.11.0)	1m 23s
PHPStan (PHP 8.1, Symfony 5.4.* + highest deps)	37s
PHPUnit (PHP 8.1, Symfony 6.4.* + highest deps, ES 7.11.0)	57s
PHPStan (PHP 8.1, Symfony 6.4.* + highest deps)	2m 48s
PHPUnit (PHP 8.2, Symfony 5.4.* + highest deps, ES 7.11.0)	1m 5s
PHPStan (PHP 8.2, Symfony 5.4.* + highest deps)	2m 40s
PHPUnit (PHP 8.2, Symfony 6.4.* + highest deps, ES 7.11.0)	59s
PHPStan (PHP 8.2, Symfony 6.4.* + highest deps)	35s
PHPUnit (PHP 8.2, Symfony 7.1.* + highest deps, ES 7.11.0)	58s
PHPStan (PHP 8.2, Symfony 7.1.* + highest deps)	37s
PHPUnit (PHP 8.3, Symfony 5.4.* + highest deps, ES 7.11.0)	1m 11s
PHPStan (PHP 8.3, Symfony 5.4.* + highest deps)	28s
PHPUnit (PHP 8.3, Symfony 6.4.* + highest deps, ES 7.11.0)	56s
PHPStan (PHP 8.3, Symfony 6.4.* + highest deps)	26s
PHPUnit (PHP 8.3, Symfony 7.1.* + highest deps, ES 7.11.0)	54s
PHPStan (PHP 8.3, Symfony 7.1.* + highest deps)	2m 37s
PHPUnit (PHP 8.4, Symfony 5.4.* + highest deps, ES 7.11.0)	1m 12s
PHPStan (PHP 8.4, Symfony 5.4.* + highest deps)	34s
PHPUnit (PHP 8.4, Symfony 6.4.* + highest deps, ES 7.11.0)	57s
PHPStan (PHP 8.4, Symfony 6.4.* + highest deps)	2m 43s
PHPUnit (PHP 8.4, Symfony 7.1.* + highest deps, ES 7.11.0)	59s
PHPStan (PHP 8.4, Symfony 7.1.* + highest deps)	35s
PHPStan (PHP 7.4, Symfony 5.4.* + lowest deps)	2m 43s
	33m 18s

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