Update symfony/yaml from v3.4.28 to v3.4.31

[violinist-bot]

If you have a high test coverage index, and your tests for this pull request are passing, it should be both safe and recommended to merge this update.

Here is a list of changes between the version you use, and the version this pull request updates to:

• 3dc414b Fix inconsistent return points.
• 5d61fdb Use assertStringContainsString when needed
• 2724c44 Use namespaced Phpunit classes
• 090881c bug #32910 [Yaml] PHP-8: Uncaught TypeError: abs() expects parameter 1 to be int or float, string given (Aleksandr Dankovtsev)
• a551af1 Remove use of ForwardCompatTrait
• 59ee8f4 [Yaml] PHP-8: Uncaught TypeError: abs() expects parameter 1 to be int or float, string given
• c90e14e Adopt @PHPUnit55Migration:risky rule of php-cs-fixer
• dab2c2e Fix deprecated phpunit annotation
• a77d5fe Replace calls to setExpectedException by Pollyfill
• 70d308f [Yaml] fix test for PHP 7.4
• ec0045b Fix assertInternalType deprecation in phpunit 9
• 39c0132 Make tests support phpunit 8
• 1a0bae0 fix(yml): fix comment in milti line value
• 051d045 fix inline handling when dumping tagged values

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