alpine-install-on-disk: use hdparm to force reread of table

alpine-install-on-disk.sh

@@ -59,6 +59,7 @@ case "$BOOT_VIA" in
 label: dos
 ,,L
 EOF
+        doas hdparm -z $DISK
         # For creation, if an existing filesystem is on the partitions
         doas mkfs.ext4 -F ${partition1}
         doas mount -t ext4 ${partition1} $rootfs_tmpdir
@@ -69,6 +70,7 @@ label: gpt
 ,500MiB,U
 ,,L
 EOF
+        doas hdparm -z $DISK
         doas mkfs.vfat ${partition1}
         doas mkfs.ext4 -F ${partition2}
         doas mount -t ext4 ${partition2} "$rootfs_tmpdir"