package/rauc: fix URL of the signed tarball
Reported-by: Yair Ben Avraham <yairba@protonmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit a9b454387cdc60a69fc2bac8a24d0e2cf3c5ddb3)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>