update container version to v38

This version includes vhost-device-gpu dependencies
which is required for vhost-device-gpu crate
more info about the crate can be found here:
rust-vmm/vhost-device#668
link to the PR that adds these dependencies
where the tag is generated can be found here:
rust-vmm/rust-vmm-container#110

Signed-off-by: Dorinda Bassey <dbassey@redhat.com>

.buildkite/autogenerate_pipeline.py

@@ -60,7 +60,7 @@
 
 # This represents the version of the rust-vmm-container used
 # for running the tests.
-CONTAINER_VERSION = "v37"
+CONTAINER_VERSION = "v38"
 # This represents the version of the Buildkite Docker plugin.
 DOCKER_PLUGIN_VERSION = "v5.3.0"