fdo#80527 fix tab order on ReadyToInstall dialog

regression from	674db242c037020626050c8de06367808d94eaaa

Change-Id: Ia02321b7450b3f19ba02fa681a50430f78f12cfd
(cherry picked from commit 54c6f08c2061f1af1a545e6b50d447f14b806057)
Signed-off-by: Andras Timar <andras.timar@collabora.com>