ci: upgrade all packages in CI

We are seeing some test failures caused by the fact that a fixed kernel,
while available, is not installed the CI image. Since cloud-init does
not itself offer a way to express precise dependency on a package
version we may use a crude replacement of upgrading all the packages at
image construction time.

The next time this happens all we need is to touch the .image-garden.mk
file, so that it is more recent than the image kept in CI cache for the
re-generation to occur.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
(cherry picked from commit f43221d9457e1fccd421dff4193dd7e67e43c230)
Signed-off-by: Ryan Lee <ryan.lee@canonical.com>

.image-garden.mk

@@ -2,6 +2,11 @@
 # All the package installation happens through cloud-init profiles defined
 # below.
 
+# NOTE: Should the kernel be out of date, just increment this value. Make will
+# re-create the image whenever the .image-garden.mk file is more recent than
+# the image itself. In reality all you need is touch(1), but this is more apt.
+unused=1
+
 # This is the cloud-init user-data profile for all Debian systems. Note that it
 # is an extension of the default profile necessary for operation of
 # image-garden.
@@ -36,6 +41,12 @@ packages:
 - python3-ttkthemes
 - swig
 - toybox
+# Update all the packages. This allows us to be on the up-to-date kernel
+# version that we cannot otherwise easily select with cloud init alone.  Note
+# that we do not need to reboot the system as image garden shuts down the image
+# after first boot. On subsequent boot we will be running the latest kernel.
+package_upgrade: true
+package_update: true
 endef
 
 # Ubuntu shares cloud-init profile with Debian.
@@ -79,6 +90,9 @@ packages:
 - python311-devel
 - swig
 - which
+# See above for rationale.
+package_upgrade: true
+package_update: true
 endef
 
 define FEDORA_CLOUD_INIT_USER_DATA_TEMPLATE
@@ -108,4 +122,7 @@ packages:
 - python3-notify2
 - python3-tkinter
 - swig
+# See above for rationale.
+package_upgrade: true
+package_update: true
 endef