Do not rely on fdisk's human readable unit output

Using the bytes output will fix an issue where the disk size is reported
either as terrabyte or also megabyte.
So far we disallowed 1TB disks but allowed 20MB disks.

scripts/cloudron-setup

@@ -15,7 +15,8 @@ readonly MINIMUM_MEMORY="990"     # this is mostly reported for 1GB main memory
 # copied from cloudron-resize-fs.sh
 readonly physical_memory=$(free -m | awk '/Mem:/ { print $2 }')
 readonly disk_device="$(for d in $(find /dev -type b); do [ "$(mountpoint -d /)" = "$(mountpoint -x $d)" ] && echo $d && break; done)"
-readonly disk_size_gb=$(fdisk -l ${disk_device} | grep "Disk ${disk_device}" | awk '{ printf "%.0f", $3 }')
+readonly disk_size_bytes=$(fdisk -l ${disk_device} | grep "Disk ${disk_device}" | awk '{ printf "%d", $5 }')
+readonly disk_size_gb=$((${disk_size_bytes}/1024/1024/1024))
 
 # verify the system has minimum requirements met
 if [[ "${physical_memory}" -lt "${MINIMUM_MEMORY}" ]]; then