Translate `library/doctest.po`

This needs to reach 100% translated.

The rendered version of this file will be available at https://docs.python.org/es/3.14/library/doctest.html once translated.
Meanwhile, the English version is shown.

Current stats for library/doctest.po:

• Fuzzy: 49
• Percent translated: 84.0%
• Entries: 321 / 382
• Untranslated: 61

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Remember to follow the steps in our Contributing Guide.

从 library/doctest.po 和项目的 Contributing Guide 开始。翻译 61 个未翻译条目并解决 49 个 fuzzy 条目，然后验证该文件已达到 100% 翻译完成度，并且渲染后的西班牙语文档不再显示英文版本。