Update phpunit/phpunit requirement from ^7.3 to ^8.3

[dependabot-preview]

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

Changelog

Sourced from phpunit/phpunit's changelog.

8.3.3 - 2019-08-03

Fixed

• Fixed #3781: MockBuilder::addMethods() and MockBuilder::onlyMethods() do not handle empty parameter array correctly

8.3.2 - 2019-08-02

Fixed

• More work on the fix for #3774: Restored name of PHPUnit\Framework\Error\Deprecated

8.3.1 - 2019-08-02

Fixed

• Fixed #3774: PHP errors, notices, etc. cannot be tested anymore with PHPUnit 8.3

8.3.0 - 2019-08-02

Added

• Implemented #3687: Introduce MockBuilder::addMethods() and MockBuilder::onlyMethods() as alternatives to MockBuilder::setMethods()
• Implemented #3741: Format class names as well as method names in TestDox output
• Implemented #3748: Add option to sort tests based on information from @small, @medium, and @large
• Added TestCase::getActualOutputForAssertion() as a wrapper for TestCase::getActualOutput() to prevent a test being marked as risky when it prints output and that output is not expected using TestCase::expectOutputString() or TestCase::expectOutputRegEx()

Changed

• Implemented #2015: Prefix all code bundled in PHAR distribution with random/unique namespace
• Implemented #3503: The error handler has been refactored to not rely on global state
• Implemented #3521: The @errorHandler annotation, which controlled a feature that was not documented and did not work correctly, does not have an effect anymore
• Implemented #3522: The TestCase::setUseErrorHandler() method, which controlled a feature that was not documented and did not work correctly, has been deprecated and does not have an effect anymore
• Implemented #3687: MockBuilder::setMethods() is now deprecated

Commits

• c319d08 Prepare release
• 05ef7ae Restore annotation
• dc43986 Newer versions of webmozart/assert depend on symfony/polyfill-ctype
• 668d8cc Merge branch '7.5' into 8.3
• 062dfa4 Reorder
• ffd0108 Fix regression introduced in 01ae44d5b6e3d27e6fa7426edfa71955261d7324
• 01ae44d Update Psalm baseline
• 9d4351d Avoid type confusion
• 555eb00 Fix type annotation
• 27d698e Update ChangeLog
• Additional commits viewable in compare view

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