build(tags): bump sure alpha aio revision

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Summary

• Bump the Sure alpha AIO revision to avoid retargeting the immutable sure-alpha/0.7.1-alpha.7-aio.2 prerelease.

What changed

• Add 0.7.1-alpha.7-aio.3 to the alpha changelog.
• Update alpha template and README release-tag references.
• Update alpha lane asset tests for the new current alpha AIO revision.

Why

• The existing alpha prerelease points at an older commit and should not be retargeted. A new AIO revision gives the current commit its own publish target.

Validation

• uv run --with pytest python -m pytest tests/test_alpha_lane_assets.py
• git diff --check

Notes

• Stable sure-aio release history remains unchanged.