Dev/release workflow

[CongkeChen]

Summary

新增基于 tag 触发的 GitHub Actions release 流水线。
该流水线会：

• 在 v* tag 时执行正式 PyPI 发布
• 在 test/v* tag 时执行 dry-run 校验，不上传 PyPI
• 校验 tag 版本和 trpc_agent_sdk.version.__version__ 一致
• 执行格式检查、flake8、pytest、构建和 twine check
• 仅在正式 v* tag 时上传 PyPI

Testing

这个 PR 本身应该只触发现有 CI，不会触发 release。
合入后可以用 dry-run tag 测试 release 流水线

[CongkeChen]

I have read the CLA Document and I hereby sign the CLA

[github-actions]

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