[Sync EN] ext/pdo: document the PHP 8.5 fetch mode changes and deprecations (#5817)

Commit: `https://github.com/php/doc-en/commit/e16d04c436e9801627139c67c1cabcb92b469ccc`
PR: `https://github.com/php/doc-en/pull/5817`

**Fichiers FR à mettre à jour**
- `reference/pdo/pdo.xml`
- `reference/pdo/pdo/construct.xml`
- `reference/pdo/pdostatement/fetchall.xml`
- `reference/pdo/pdostatement/setattribute.xml`
- `reference/pdo/pdostatement/setfetchmode.xml`
