Remove version from compose files for #643

This directive is now obsolete, causes more noise in the GHA workflow
run logs.

https://forums.docker.com/t/docker-compose-yml-version-is-obsolete/141313

src/content/docker-compose.yml

@@ -1,6 +1,5 @@
 # This extends the OSCAL build container which should be located at:
 # ../../vendor/oscal/build/docker-compose.yml
-version: '3'
 services:
   cli:
     volumes: