Temporarily disable l1um build

The l1um build is failing on this branch, disable for now to get preview builds.

Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>

build_release.sh

@@ -19,7 +19,7 @@ die () {
 
 # boards to build
 boards=("librem_13v2" "librem_15v3" "librem_13v4" "librem_15v4" \
-	"librem_mini" "librem_mini_v2" "librem_l1um" "librem_14")
+	"librem_mini" "librem_mini_v2" "librem_14")
 
 # check release tags
 TAG=$(git describe --tags --dirty)