refactor: do not use RuntimeError in hathorlib/client.py

This was suggested in https://github.com/HathorNetwork/python-hathorlib/pull/10#discussion_r855955177

We need to make sure this change will not affect other projects using this lib, and if it does, update them as well.

Probably this will generate a new Major version since it will be a breaking change.

从 hathorlib/client.py 以及提出此次重构的 pull request #10 中的讨论开始。确定 RuntimeError 的使用方式，并判断更改它是否会影响其他使用该库的项目。替换方案达成一致、依赖项目已在需要时更新，并且兼容性影响得到处理后，即视为完成。

由索引模型根据 Issue 内容生成。