Fix PHP 8.5 reflection deprecations

[kalifg]

Summary

• Remove deprecated ReflectionMethod::setAccessible() and ReflectionProperty::setAccessible() calls from the loader path.
• Replace ReflectionParameter::getClass() usage with ReflectionParameter::getType() / ReflectionNamedType handling.
• Target the maintained fork at PHP ^8.4, upgrade the dev test runner to PHPUnit 11, and clean up PHPUnit/PHP deprecations in the tests.
• Add GitHub Actions coverage for PHP 8.4 and 8.5.

Verification

• composer validate --strict --no-check-lock
• php -l src/Nelmio/Alice/Loader/Base.php && php -l tests/Nelmio/Alice/Loader/BaseTest.php && php -l tests/Nelmio/Alice/FixturesTest.php && php -l tests/Nelmio/Alice/fixtures/User.php && php -l phpunit.xml.dist
• rg -n '@expectedException|setExpectedException|getMock\\(|assertRegExp|returnValue\\(|setAccessible|getClass\\(' src tests phpunit.xml.dist || true
• vendor/bin/phpunit --display-all-issues --fail-on-phpunit-deprecation on PHP 8.4.7
• docker run --rm -v "$PWD":/app -w /app php:8.5-cli php vendor/bin/phpunit --display-all-issues --fail-on-phpunit-deprecation on PHP 8.5.5

Notes

• This intentionally stays scoped to PHP 8.4/8.5 readiness for the existing fork. It does not attempt an upstream Alice migration. I feel like this is the path of least resistance for PHP 8.5 even though hopefully soon (after ORM 3.x and Symfony 7) we will get compatible with modern Alice abandon this fork.