Add PHP 8.5 to CI matrix

[Copilot]

Extends the CI test matrix to include PHP 8.5 alongside the existing 8.1–8.4 versions.

Changes

• .github/workflows/ci.yml: Added "8.5" to the php matrix, adding 2 new job combinations (MySQL + SQLite)

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[Copilot]

Pull request overview

Extends the GitHub Actions CI workflow to run the existing test/install steps on PHP 8.5 in addition to the currently covered PHP 8.1–8.4 versions.

Changes:

• Added PHP 8.5 to the CI matrix, expanding coverage across existing DB variants (MySQL + SQLite).

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[Copilot]

Adding PHP 8.5 to the matrix will run the job on 8.5, but the Composer dependency resolution is still pinned to PHP 8.1.33 via composer.json's config.platform.php. That means the new 8.5 job won’t validate that dependencies/lockfile are resolvable under PHP 8.5 (it will install as if on 8.1). If the intent is to ensure full compatibility per PHP version, consider overriding/removing the platform PHP version for CI runs (or setting it dynamically from matrix.php).