feat: auth0-php v9 compatibility (6.x beta groundwork)

[kishore7snehil]

Auth0 Symfony SDK - auth0-php v9 compatibility

This PR moves the bundle onto auth0-php v9 and lands the groundwork for the upcoming 6.x major. It targets the v6 mainline branch. Version bumps (.version, Service::VERSION, CHANGELOG) are intentionally not included here - those ship in a separate release/6.0.0-beta.0 PR, mirroring the auth0-php release model.

What's New

• auth0-php v9: the bundle now requires auth0/auth0-php ^9.0@beta, whose Management API is generated from Auth0's OpenAPI specs (typed requests/responses, property-access sub-clients, pagers).
• Service::getManagement(): a new accessor that returns a v9 Management client built from the bundle's existing domain / client_id / client_secret configuration. It fetches and caches a client-credentials token for you.
• PHP 8.2+: the supported PHP floor is raised to 8.2.
• Refreshed 6.4 LTS example: the sample app is rebuilt onto Symfony 6.4 with a lean bundle set and a Management API explorer demonstrating getManagement().

Breaking Changes

Area	5.x	6.x
auth0/auth0-php	^8.19	^9.0
PHP	^8.1	>=8.2
Management access	$auth0->getSdk()->management()	$auth0->getManagement()
Management responses	raw PSR-7, HttpResponse::decodeContent()	typed objects

The v8-style getSdk()->management() is non-functional in auth0-php v9 and throws a TypeError. Use getManagement() instead.

What's NOT Affected

Authentication flows are unchanged. The authenticator, authorizer, user provider, session store, and the bundled authentication controllers behave exactly as they did in 5.x. Login, callback, profile, and logout were verified end-to-end against v9.

Migration Example

// 5.x
$management = $auth0->getSdk()->management();
$response = $management->users()->getAll(['per_page' => 25]);
$users = HttpResponse::decodeContent($response);

// 6.x
$management = $auth0->getManagement();
$users = $management->users->list(
    new ListUsersRequestParameters(['perPage' => 25])
);
foreach ($users as $user) {
    echo $user->getEmail();
}

Documentation

• README.md: PHP 8.2 requirement, a new "Accessing the Management API" section, and a consolidated support table.
• UPGRADING.md: a new "5.x to 6.x" section covering the dependency bump and the Management API migration.

CI

• tests.yml now also runs on pushes to v6 (PRs into v6 already run via the unfiltered pull_request trigger).

Beta Notice

This is groundwork for a beta release. While the authentication surface is stable, the Management API in auth0-php v9 is itself in beta and minor adjustments may occur before the final 6.0.0.

[rmad17]

composer.json mentions the version as ^9.0@beta". Is that intentional?

[rmad17]

Do we need to change this version to 6.x.x?