Add PHP 8 attributes support #15

Job	Run time
Run tests PHP 7.1 Symfony 3.* highest	1m 50s
Run tests PHP 7.1 Symfony 4.* highest	1m 53s
Run tests PHP 7.2 Symfony 3.* highest	1m 59s
Run tests PHP 7.2 Symfony 4.* highest	1m 45s
Run tests PHP 7.2 Symfony 5.* highest	2m 7s
Run tests PHP 7.3 Symfony 3.* highest	1m 36s
Run tests PHP 7.3 Symfony 4.* highest	1m 21s
Run tests PHP 7.3 Symfony 5.* highest	1m 48s
Run tests PHP 7.4 Symfony 3.* highest	1m 50s
Run tests PHP 7.4 Symfony 4.* highest	1m 29s
Run tests PHP 7.4 Symfony 5.* highest	1m 44s
Run tests PHP 8.0 Symfony 4.* highest	29s
Run tests PHP 8.0 Symfony 5.* highest	32s
Run tests PHP 8.1 Symfony 4.* highest	1m 27s
Run tests PHP 8.1 Symfony 5.* highest	1m 57s
Run tests PHP 8.1 Symfony 6.* highest	2m 19s
Run tests PHP 8.2 Symfony 4.* highest	1m 37s
Run tests PHP 8.2 Symfony 5.* highest	2m 0s
Run tests PHP 8.2 Symfony 6.* highest	2m 26s
Run tests PHP 7.1 Symfony 3.* lowest	1m 47s
	33m 56s

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