Add support for Guzzle 8 and PSR-7 / promises 3.x

[HecFranco]

Summary

• Widen Composer constraints to allow guzzlehttp/guzzle ^8.0, guzzlehttp/psr7 ^3.0, and guzzlehttp/promises ^3.0 while keeping Guzzle 6/7 support.
• Update middlewares to resolve HTTP responses via method_exists(..., 'getResponse') instead of hard-typing Guzzle 7's RequestException, so logging and event dispatch work with Guzzle 8's exception hierarchy.

Why a separate PR from #355

#355 (draft) drops Guzzle 6 and Symfony 5 and updates CI. This PR is intentionally additive: it keeps existing supported majors and only adds the runtime compatibility needed for Guzzle 8. Happy to rebase/align with #355 if you prefer that direction.

Test plan

• Install with Guzzle 7 and run the test suite
• Install with Guzzle 8 / psr7 3 / promises 3 and confirm Composer resolves
• Trigger a failed request and verify Log / SymfonyLog / EventDispatch middlewares still capture the response when present

Related issue: will link after creation.

Made with Cursor

[HecFranco]

Closes #356

[HecFranco]

Thank you for your time reviewing this PR!

CI is green on the supported PHP/Symfony matrix. Could you please consider approving and merging when you have a moment? This would unblock projects that need Guzzle 8 (with PSR-7 / promises 3.x) while remaining compatible with Guzzle 6/7.

Happy to adjust anything if needed. Thanks again!

[HecFranco]

Hi @gregurco — gentle ping on this one.

CI is green across the PHP/Symfony matrix. This PR is intentionally additive (keeps Guzzle 6/7 + Symfony 5) and only adds Guzzle 8 / PSR-7 3 / promises 3 support, plus a small middleware tweak so response extraction works with Guzzle 8’s exception hierarchy.

I saw your draft #355, which takes a broader approach (dropping older majors / CI updates). Happy to follow whichever direction you prefer:

1. Merge this PR as a minimal unblock for Guzzle 8, and fold the larger cleanup into Support Guzzle 8.0 #355 later, or
2. Close this in favor of Support Guzzle 8.0 #355 — I can rebase/adapt the middleware compatibility bits onto your branch if useful.

This is currently blocking our upgrade to Guzzle 8. Thanks for taking a look when you have a moment!

[gregurco]

@HecFranco thank you for the contribution 🙌