Fix deprecation warnings

[BerntWinqvist]

Fix these deprecation warnings:

• Creation of dynamic property OneLogin\api\OneLoginClient::$clientId
  • https://www.php.net/manual/en/migration82.deprecated.php
• Implicitly nullable parameter: $previous
  • https://www.php.net/manual/en/migration84.deprecated.php

[Copilot]

Pull request overview

This PR addresses PHP deprecation warnings introduced in newer PHP versions by aligning property declarations with actual runtime usage and by making an exception constructor parameter explicitly nullable.

Changes:

• Declare OneLoginClient::$clientId (camelCase) to prevent PHP 8.2 “dynamic property” deprecation warnings.
• Update OneLoginException::__construct() to use ?\Throwable $previous = null to avoid PHP 8.4 “implicitly nullable parameter” deprecation warnings.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/OneLoginClient.php	Renames/declares the client ID property as clientId to stop dynamic property creation.
src/exceptions/OneLoginException.php	Makes $previous explicitly nullable (?\Throwable) to satisfy PHP 8.4 deprecation rules.

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[Subterrane]

Thanks @BerntWinqvist — both deprecation fixes here are now in master via #35, which kept $clientID as a @deprecated alias of the new $clientId to avoid a breaking change for existing callers. The OneLoginException nullable-$previous fix landed identically. Closing as superseded.