chore(deps): update dependency phpunit/phpunit to v9.6.26

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
phpunit/phpunit (source)	9.6.25 -> 9.6.26

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Release Notes

sebastianbergmann/phpunit (phpunit/phpunit)

v9.6.26: PHPUnit 9.6.26

Compare Source

Changed

• Implement __serialize() in addition to __sleep() (which will be deprecated in PHP 8.5)

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