[packit] 1.21.0 upstream release
    
    Upstream tag: go1.21.0
    Upstream commit: c19c4c56
    
    If you need to do any change in this pull request, you need to locally fetch the source branch of it and push it (with a fix) to your fork (as it is not possible to push to the branch created in the Packit’s fork):
    ```
    git fetch https://src.fedoraproject.org/forks/packit/rpms/golang.git refs/heads/*:refs/remotes/packit/*
    git checkout packit/1.21.0-rawhide-update-pull_from_upstream
    ```