Update phpunit/phpunit requirement from ^8.4 to ^9.6

[dependabot[bot]]

Updates the requirements on phpunit/phpunit to permit the latest version.

Changelog

Sourced from phpunit/phpunit's changelog.

[9.6.9] - 2023-06-11

Fixed

• #5405: XML configuration migration does not migrate whitelist/file elements
• Always use X.Y.Z version number (and not just X.Y) of PHPUnit's version when checking whether a PHAR-distributed extension is compatible

[9.6.8] - 2023-05-11

Fixed

• #5345: No stack trace shown for previous exceptions during bootstrap

[9.6.7] - 2023-04-14

Fixed

• Tests that have @doesNotPerformAssertions do not contribute to code coverage

[9.6.6] - 2023-03-27

Fixed

• #5270: GlobalState::getIniSettingsAsString() generates code that triggers warnings

[9.6.5] - 2023-03-09

Changed

• Backported the HTML and CSS improvements made to the --testdox-html from PHPUnit 10

Fixed

• #5205: Wrong default value for optional parameter of PHPUnit\Util\Test::parseTestMethodAnnotations() causes ReflectionException

[9.6.4] - 2023-02-27

Fixed

• #5186: SBOM does not validate

[9.6.3] - 2023-02-04

Fixed

• #5164: markTestSkipped() not handled correctly when called in "before first test" method

[9.6.2] - 2023-02-04

Fixed

... (truncated)

Commits

• a9aceaf Prepare release
• 324512e Closes #5405
• 70e8497 Update ChangeLog
• 284eedd Use Version::id() instead of Version::series() to check extension compatibility
• 8eae9e1 Merge branch '8.5' into 9.6
• f37fc18 Disable phpdoc_to_comment fixer (because it renders psalm-suppress annotation...
• 8a8e449 Fix: Avoid multiline parameter lists
• 0da2376 Merge branch '8.5' into 9.6
• f7e7556 Delete superfluous tests
• 72c58ad Also test --filter option with both configuration and argument
• Additional commits viewable in compare view

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