Run restorecon for nm-dispatcher directory only if it exists
    
    Unconditional execution can make the rpm scriptlet failing:
    
    Running scriptlet: selinux-policy-targeted-36.9-1.fc36.noarch             4/4
    /usr/sbin/restorecon: SELinux: Could not get canonical path for /etc/NetworkManager/dispatcher.d restorecon: No such file or directory.
    warning: %posttrans(selinux-policy-targeted-36.9-1.fc36.noarch) scriptlet failed, exit status 255
    
    Resolves: rhbz#2082547