因此，我一直在尝试更新到 Ubuntu 21.10，但是在准备更新后，我收到此消息：
W:Updating from such a repository can't be done securely, and is therefore disabled by default.,
W:See apt-secure(8) manpage for repository creation and user configuration details.,
W:GPG error: https://dl.winehq.org/wine-builds/ubuntu impish InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 76F1A20FF987672F,
E:The repository 'https://dl.winehq.org/wine-builds/ubuntu impish InRelease' is not signed.,
W:Updating from such a repository can't be done securely, and is therefore disabled by default.,
W:See apt-secure(8) manpage for repository creation and user configuration details.,
W:Target Sources (restricted/source/Sources) is configured multiple times in /etc/apt/sources.list:2 and /etc/apt/sources.list:7
我尝试过其他类似问题的解决方案，但似乎都不起作用。我不是 Linux 专家，所以你们能给我一些关于如何解决这个问题的想法吗？