MT#58926 Vagrant: ensure to have libxmu6 available

We get the following error message in /var/log/vboxadd-install.log,
/var/log/deployment-installer-debug.log, /var/log/daemon.log +
/var/log/syslog:

| /opt/VBoxGuestAdditions-7.0.6/bin/VBoxClient: error while loading shared libraries: libXmu.so.6: cannot open shared object file: No such file or directory

This is caused by missing libxmu6:

| [sipwise-lab-trunk] sipwise@spce:~$ /opt/VBoxGuestAdditions-7.0.6/bin/VBoxClient --help
| /opt/VBoxGuestAdditions-7.0.6/bin/VBoxClient: error while loading shared libraries: libXmu.so.6: cannot open shared object file: No such file or directory
| [sipwise-lab-trunk] sipwise@spce:~$ sudo apt install libxmu6
| Reading package lists... Done
| Building dependency tree... Done
| Reading state information... Done
| The following NEW packages will be installed:
|   libxmu6
| 0 upgraded, 1 newly installed, 0 to remove and 83 not upgraded.
| Need to get 60.1 kB of archives.
| After this operation, 143 kB of additional disk space will be used.
| Get:1 https://debian.sipwise.com/debian bookworm/main amd64 libxmu6 amd64 2:1.1.3-3 [60.1 kB]
| Fetched 60.1 kB in 0s (199 kB/s)
| [...]
| [sipwise-lab-trunk] sipwise@spce:~$ /opt/VBoxGuestAdditions-7.0.6/bin/VBoxClient --help
| Oracle VM VirtualBox VBoxClient 7.0.6
| Copyright (C) 2005-2023 Oracle and/or its affiliates
|
| Usage: VBoxClient --clipboard|--draganddrop|--checkhostversion|--seamless|--vmsvga|--vmsvga-session
| [-d|--nodaemon]
|
| Options:
| [...]

It looks like lack of libxmu6 doesn't cause any actual problems for our
use case (we don't use X.org at all), though given that libxmu6 is a
small library package, let's try to get it working as expected and avoid
the alarming errors on the logs.

Thanks Guillem Jover for spotting and reporting

Change-Id: I65f3dd496a4026f04fd9944fd7cc43d6abbdf336

templates/scripts/includes/deployment.sh

@@ -1013,8 +1013,8 @@ vagrant_configuration() {
   # bzip2, linux-headers-amd64 and make are required for VirtualBox Guest Additions installer
   # less + sudo are required for Vagrant itself
   echo "Installing software for VirtualBox Guest Additions installer"
-  if ! grml-chroot "${TARGET}" apt-get -y install bzip2 less linux-headers-amd64 make sudo ; then
-    die "Error: failed to install 'bzip2 less linux-headers-amd64 make sudo' packages."
+  if ! grml-chroot "${TARGET}" apt-get -y install bzip2 less libxmu6 linux-headers-amd64 make sudo ; then
+    die "Error: failed to install 'bzip2 less libxmu6 linux-headers-amd64 make sudo' packages."
   fi
 
   vagrant_ssh_pub_key='/var/tmp/id_rsa_sipwise.pub'