Update URL for ubuntu live

Updates to a more stable URL since daily-live changed to the next
version already

roles/netbootxyz/templates/menu/ubuntu.ipxe.j2

@@ -81,6 +81,7 @@ boot
 {% if key == kernel_name %}
 set kernel_url ${live_endpoint}{{ value.path }}
 set codename {{ value.codename }}
+set version_number {{ value.version }}
 {% endif %}
 {% endfor %}
 goto sub_boot
@@ -90,7 +91,7 @@ goto sub_boot
 :sub_boot
 imgfree
 echo Loading Ubuntu Subiquity Network Installer...
-kernel ${kernel_url}vmlinuz root=/dev/ram0 ramdisk_size=1500000 initrd=initrd ip=dhcp url=http://cdimage.ubuntu.com/ubuntu-server/daily-live/current/${codename}-live-server-${arch_a}.iso
+kernel ${kernel_url}vmlinuz root=/dev/ram0 ramdisk_size=1500000 initrd=initrd ip=dhcp url=http://releases.ubuntu.com/${codename}/ubuntu-${version_number}-live-server-${arch_a}.iso
 initrd ${kernel_url}initrd
 echo
 echo MD5sums: