Remove `Requires(post)` on firewalld-filesystem.
    
    The firewalld zone was dropped in 37290cc.
    
    The `%{firewalld_reload}` macro (provided by firewalld-filesystem
    is used in the macro but it gets encoded in the RPM at build time
    so it only needs to be a buildrequires, which it is already.
    
    Also I'll note that the macro properly handles firewalld not being
    installed:
    
    ```
    [core@localhost ~]$ rpm -E '%{firewalld_reload}'
    test -f /usr/bin/firewall-cmd && firewall-cmd --reload --quiet || :
    ```
    
    So we should be good to go.