feat: add httpx2 instrumentation

[HosseinNejatiJavaremi]

Summary

• Add httpx2 instrumentation mirroring existing httpx support
• Instrument httpx2.Client.send and httpx2.AsyncClient.send for external HTTP spans
• Instrument httpcore2 for distributed tracing header propagation
• Gate registration to Python 3.10+ (httpx2 requirement)
• Add tests, CI matrix entry, and supported-technologies docs

Closes #2696

Test plan

• pytest -m httpx2 tests/instrumentation/httpx2_tests.py tests/instrumentation/asyncio_tests/httpx2_tests.py (18 passed)

Made with Cursor

[cla-checker-service]

❌ Author of the following commits did not sign a Contributor Agreement:
4767cc0, 2a4c68b

Please, read and sign the above mentioned agreement if you want to contribute to this project

[github-actions]

🤖 GitHub comments

Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)

[HosseinNejatiJavaremi]

CLA check is still failing on my side even after re-signing the Contributor Agreement with GitHub user HosseinNejatiJavaremi and email hosseinnejati14@gmail.com (same email as my merged PR #2682). Happy to re-sign or provide any extra info if needed.

Thanks for the review.

[xrmx]

@HosseinNejatiJavaremi as I said already please wait for feedback on the issue before opening PRs.

[HosseinNejatiJavaremi]

@xrmx Thanks for the feedback. I waited ~3 weeks on #2696 before opening the PR — httpx2 adoption is picking up and I wanted to help move it forward.

Happy to close the PR and follow your process on the issue.

If the supported path is now OpenTelemetry / EDOT for Python, I’d prefer to migrate there rather than invest more in this repo. If apm-agent-python is still the right place for httpx2, I’m happy to contribute — just need clarity on direction.

Thanks.