chore: prepare h3x v0.6.0-beta.2

[eareimu]

Release prep

Prepare h3x v0.6.0-beta.2 and update its dquic dependency to v0.7.0-beta.2.

Draft tag message

# h3x v0.6.0-beta.2

## Changes

- Update the dquic backend dependency to `dquic` v0.7.0-beta.2.
- Keep tag-CI GitHub Release generation aligned with annotated tag notes and prerelease classification.

## Published crate

- `h3x` v0.6.0-beta.2

Release gates

• Target branch: main
• Planned tag: v0.6.0-beta.2
• Initial/incremental: incremental
• Surface: crates.io + tag-CI GitHub Release

Dependency wait conditions

dquic v0.7.0-beta.2 is published and visible on crates.io.

Notes

Final merge/tag remains gated on release-relevant PR CI and explicit merge/tag approval.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
see 4 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.