Day29 发送带附件邮件的示例代码缺少 email.attach(attachment)

在 Day21-30/29.Python发送邮件和短信.md 中，「发送带附件的邮件」一节的示例代码存在一个小问题：
代码虽然创建了 attachment 对象并设置了相关头部信息，但没有调用 email.attach(attachment) 将附件添加到邮件主体中。这会导致实际发送的邮件不包含附件。

问题代码位置：
Python

with open(f'resources/王大锤离职证明.docx', 'rb') as file:
attachment = MIMEText(file.read(), 'base64', 'utf-8')
attachment['content-type'] = 'application/octet-stream'
filename = quote('王大锤离职证明.docx')
attachment['content-disposition'] = f'attachment; filename="{filename}"'

此处缺少 email.attach(attachment)

建议修复：
在 with 代码块结束后（或内部末尾）添加：
Python

email.attach(attachment)
感谢作者和维护团队的辛勤付出，这个项目帮助了很多初学者！

Open Day21-30/29.Python发送邮件和短信.md and find the “发送带附件的邮件” example. Read the attachment-building block, then ensure the example attaches the created attachment to the email message. Done means the documented example includes the attachment and accurately sends it with the message.