spec: `systemd-ukify` should depend on `systemd-boot`
    
    `systemd-ukify` requires `/usr/lib/systemd/boot/efi/{addonx64,linuxx64}.efi.stub` to work properly, e.g.
    
    ```
    Traceback (most recent call last):
      File "/usr/bin/ukify", line 1660, in <module>
        main()
      File "/usr/bin/ukify", line 1648, in main
        check_inputs(opts)
      File "/usr/bin/ukify", line 390, in check_inputs
        value.open().close()
      File "/usr/lib64/python3.9/pathlib.py", line 1252, in open
        return io.open(self, mode, buffering, encoding, errors, newline,
      File "/usr/lib64/python3.9/pathlib.py", line 1120, in _opener
        return self._accessor.open(self, flags, mode)
    FileNotFoundError: [Errno 2] No such file or directory: '/usr/lib/systemd/boot/efi/addonx64.efi.stub'
    ```
    
    `/usr/lib/systemd/boot/efi/{addonx64,linuxx64}.efi.stub` are now contained in `systemd-boot-unsigned` sub-package so adding a dependency on it seems like the easiest solution.
    
    Originally reported by: Vitaly Kuznetsov <vkuznets@redhat.com> in https://issues.redhat.com/browse/RHEL-33990
    
    Signed-off-by: Jan Macku <jamacku@redhat.com>