package/weston: remove md5 and sha1 hashes

Since weston 10.0.0, md5 and sha1 hashes are not published
with the release announce email.

The values were probably calculated locally, so remove them
since upstream provide stronger hashes.

Fixes:
f67a6e9b

Signed-off-by: Romain Naour <romain.naour@smile.fr>
Cc: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>