Ship /etc/kernel/postinst.d hook to ensure the

/var/run/reboot-required file is created (avoid the need to have
update-notifier-common installed)

README.md

@@ -204,10 +204,6 @@ Supported Options Reference
  Automatically reboot *WITHOUT CONFIRMATION* if the file
  /var/run/reboot-required is found after the upgrade
 
- Please note that you need the update-notifier-common package (only
- available in Ubuntu) or a custom hook in /etc/kernel/postinst.d to
- generate the reboot-required file.
-
 * `Acquire::http::Dl-Limit` - integer (default:0)
 
  Use apt bandwidth limit feature when fetching the upgrades. The

debian/dirs

@@ -2,3 +2,4 @@ usr/bin
 var/log/unattended-upgrades
 etc/logrotate.d
 etc/apt/apt.conf.d
+etc/kernel/postinst.d

kernel/postinst.d/unattended-upgrades

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+if [ -d /var/run ]; then
+   touch /var/run/reboot-required
+fi

setup.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 
+import glob
 from setuptools import setup
 from DistUtilsExtra.command import (
     build_extra,
@@ -24,6 +25,8 @@
                 ["man/unattended-upgrade.8"]),
             ('../etc/pm/sleep.d/',
                 ["pm/sleep.d/10_unattended-upgrades-hibernate"]),
+            ('../etc/kernel/postinst.d/',
+                glob.glob("kernel/postinst.d/*")),
             ('../usr/share/apport/package-hooks/',
                 ["debian/source_unattended-upgrades.py"])
         ],