minor #4162 DX: Drop symfony/lts (keradus)
minor #4162 DX: Drop symfony/lts (keradus)

This PR was squashed before being merged into the 2.12 branch (closes #4162).

Discussion
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DX: Drop symfony/lts

Replaces #4138

Commits
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6b3fc01e DX: Drop symfony/lts

Slamdunk/PHP-CS-Fixer,kubawerlos/PHP-CS-Fixer,gharlan/PHP-CS-Fixer,Slamdunk/PHP-CS-Fixer,SpacePossum/PHP-CS-Fixer,FriendsOfPHP/PHP-CS-Fixer,FriendsOfPHP/PHP-CS-Fixer,keradus/PHP-CS-Fixer,keradus/PHP-CS-Fixer,SpacePossum/PHP-CS-Fixer,GrahamCampbell/PHP-CS-Fixer,gharlan/PHP-CS-Fixer,GrahamCampbell/PHP-CS-Fixer,kubawerlos/PHP-CS-Fixer