fix: remove the obsolete version attribute

[Akuukis]

Avoid potential confusion on running ./run.py from kobo-install as suggested by the warning message.

before

$ ./run.py 
WARN[0000] /<redacted-path>/kobo-docker/docker-compose.maintenance.yml: the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion 
WARN[0000] /<redacted-path>/kobo-docker/tmp01/docker-compose.maintenance.override.yml: the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion 
WARN[0000] /<redacted-path>/kobo-docker/tmp01/docker-compose.frontend.yml: the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion 
WARN[0000] /<redacted-path>/kobo-docker/tmp01/docker-compose.frontend.override.yml: the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion 
WARN[0000] /<redacted-path>/kobo-docker/tmp01/docker-compose.maintenance.yml: the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion 
WARN[0000] /<redacted-path>/kobo-docker/tmp01/docker-compose.maintenance.override.yml: the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion 
WARN[0000] /<redacted-path>/kobo-docker/tmp01/docker-compose.backend.yml: the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion 
WARN[0000] /<redacted-path>/kobo-docker/tmp01/docker-compose.backend.override.yml: the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion 
[+] Running 5/5
...

after

$ ./run.py 
[+] Running 5/5
...

[noliveleger]

Won't append until we support docker compose v1. But that's in the backlog.