MT#16911 Depend on grml-debootstrap >=0.74, providing grub-pc/install_devices support

We're hitting "Error: File not found" GRUB errors during wheezy->jessie
upgrades. While this doesn't cause any hard problems since the boot
still continues automatically we should ensure that the grub-pc
package knows where to install the bootloader.

grml-debootstrap >=0.74 provides the according grub-pc/install_devices
debconf support.

Change-Id: I6062888a132389b279c0ce4987334866da98a689

deployment.sh

@@ -282,7 +282,7 @@ fai_upgrade() {
 }
 
 grml_debootstrap_upgrade() {
-  local required_version=0.67
+  local required_version=0.74
   local present_version=$(dpkg-query --show --showformat='${Version}' grml-debootstrap)
 
   if dpkg --compare-versions $present_version lt $required_version ; then