fix: support Guzzle 8

[kOld]

Summary

This package currently requires Guzzle ^7.9.3 even though its integration uses the PSR-compatible Guzzle client. This widens the requirement to allow Guzzle 8.

Guzzle 8 has stricter constructor configuration types, so the request timeout now uses Laravel's typed config accessor: config()->integer('openai.request_timeout', 30).

No workflow changes are needed: the existing prefer-stable matrix resolves Guzzle 8 for Laravel 13, while Laravel 11/12 and prefer-lowest remain on Guzzle 7 because of their framework constraints.

Validation

• composer validate --strict
• Composer dry-run: Laravel 13 + prefer-stable resolves Guzzle 8.0.2
• Composer dry-run: Laravel 13 + prefer-lowest resolves Guzzle 7.9.x
• Composer dry-run: Laravel 11/12 + prefer-stable resolve Guzzle 7.15.3
• composer test with Laravel 13 and Guzzle 8: Pint, PHPStan, architecture/facade/service-provider tests; 21 passed, 27 assertions
• git diff --check

Related work

I searched the open pull requests for Guzzle-related work. PR #127 is about a PSR-18-compatible Laravel HTTP wrapper, not Guzzle 8 support, so this addresses a separate compatibility gap.

[iBotPeaches]

Hmm this matrix is going to get insane if we have to add Guzzle to it. On top of Laravel, PHP and Pest. I can probably drop Pest to only 4/5. I'll wait till this stabilizes and brainstorm.

[kOld]

Closing this draft for now so we do not leave exploratory compatibility work open while upstream direction is unsettled. Thank you for the review.

[iBotPeaches]

Yeah no worries. I appreciate the work. I will take it from wherever you end it. I just saw your earlier commits of another matrix which got me thinking.