Support PHP 8.5 and work around deprecated method aliases and casts

[clue]

This changeset adds support for PHP 8.5 and works around deprecated method aliases and casts. This is part 15 of reviving Ratchet as discussed in #1054, unblocking more future progress.

With these changes applied, the existing test suite recently updated with #1117, #1099, #1097, #1096, #1094, #1093 and #1092 now works fine on PHP 8.5 at last. This aligns with the broader PHP 8.5 rollout across the ReactPHP ecosystem, including the just-released ratchet/rfc6455 v0.4.1 covering ratchetphp/RFC6455#75 and ratchetphp/RFC6455#77, plus recent upstream PHP 8.5 fixes in reactphp/socket#325, reactphp/event-loop#282, and clue/framework-x#297 and related work. Thanks to Ratchet's existing multi-version constraints, no composer.json changes are needed. Composer transparently picks up these latest minor releases on PHP 8.5+ while remaining compatible with legacy PHP 5.4+ on older versions.

Specifically, this works around SplObjectStorage::attach(), detach(), and contains() method aliases (now using offsetSet(), offsetUnset(), and offsetExists() instead) and the non-canonical (boolean) cast (now using (bool) instead). The test suite also guards ReflectionMethod/Property::setAccessible() calls with if (PHP_VERSION_ID < 80100) since these became no-ops in PHP 8.1+ and were formally deprecated in PHP 8.5.

Overall, this required quite a massive effort. If you want to support this project, please consider sponsoring @reactphp ❤️

Builds on top of #1117, #1099, #1097, #1096, #1094, #1093, #1092, #1091 and #1088, one step closer to reviving Ratchet as discussed in #1054

[Copilot]

Pull request overview

This PR updates Ratchet to run cleanly on PHP 8.5 by removing usages of newly-deprecated aliases/casts and updating the CI matrix to include PHP 8.5, keeping compatibility with older PHP versions via conditional reflection access.

Changes:

• Replace SplObjectStorage::{attach,detach,contains}() alias calls with offset{Set,Unset,Exists}() across runtime code and tests.
• Replace non-canonical (boolean) casts with (bool).
• Guard ReflectionMethod/Property::setAccessible() calls for PHP < 8.1 and add PHP 8.5 to CI.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/unit/Wamp/TopicManagerTest.php	Avoid deprecated reflection setAccessible() on PHP 8.1+; update subscription membership checks to offsetExists().
tests/unit/Wamp/ServerProtocolTest.php	Guard reflection setAccessible() for PHP < 8.1.
tests/unit/Session/SessionProviderTest.php	Guard reflection setAccessible() for PHP < 8.1.
tests/unit/AppTest.php	Guard reflection setAccessible() for PHP < 8.1.
tests/unit/AbstractConnectionDecoratorTest.php	Guard reflection setAccessible() for PHP < 8.1.
src/Ratchet/WebSocket/WsServer.php	Replace deprecated SplObjectStorage alias methods with offset* equivalents.
src/Ratchet/Wamp/TopicManager.php	Replace deprecated SplObjectStorage alias methods with offset* equivalents for subscription tracking.
src/Ratchet/Wamp/Topic.php	Replace deprecated SplObjectStorage alias methods with offset* equivalents for subscriber tracking.
src/Ratchet/Wamp/ServerProtocol.php	Replace deprecated SplObjectStorage alias methods; switch (boolean) to (bool) for exclude handling.
src/Ratchet/Server/FlashPolicy.php	Switch (boolean) to (bool) when storing the $secure flag.
.github/workflows/ci.yml	Add PHP 8.5 to test matrix; update action versions.

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