`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>

(cherry picked from commit b9ec39c0efa664f18666c8c94140f3bbfb0bca3b)

Resolves: RHEL-33990