## Summary

Two small, related cleanups ahead of the v0.7.3 release line.

- Bump the Python SDK from `0.7.0` to `0.7.3` (`pyproject.toml`,
`cubesandbox/__init__.py`).
- Bump the Node SDK from `0.3.0` to `0.7.3` (`package.json`,
`package-lock.json`, `src/index.ts`).
- Refresh the version badges in the Python and Node READMEs so they
match the new versions.
- Fix the Go SDK release workflow so the pushed tag uses the
`sdk/go/v<version>` form required for Go modules. The tag is now built
from a dedicated `module_tag` step output instead of being reassembled
inline, and the job summary reports the same value.

## Why

The SDKs had drifted from the release version, so published metadata and
the badges advertised stale numbers. Separately, Go module tags must
embed the `v` prefix in the path (`sdk/go/v0.7.3`), and the previous
inline construction dropped it in the summary output while the tag
itself was hand-built at each call site. A single source of truth keeps
the two consistent.

## Testing

- Version strings verified in all touched manifests and source files.
- Workflow change is limited to output plumbing; the tag value used for
`git rev-parse` and `git push` is now consistent across steps.

## Notes

- No functional SDK API changes; only version metadata and CI tag
handling.

Signed-off-by: jinlong <jinlong@tencent.com>