feat(docs): removed deprecated version line in docker compose files

[JordyEGNL]

This PR removes the version: '3.8' lines in all docker-compose files.

It also removes this warning message shown in the console.

Closes #8256

More information can be found here: https://github.com/compose-spec/compose-spec/blob/master/04-version-and-name.md
And here: mailcow/mailcow-dockerized#5797

[JordyEGNL]

I am unsure if the version string can also be removed from hwaccel.ml.yml and hwaccel.transcoding.yml because I dont use those.

[alextran1502]

if you use older version of docker and docker compose what would happen?

[danieldietzler]

if you use older version of docker and docker compose what would happen?

AFAIK this should always be fine. Version 3.x is the default for a long time, so the name field is still the part that gives the version limit

[danieldietzler]

LGTM!

[JordyEGNL]

if you use older version of docker and docker compose what would happen?

This is what the official documentation says
The top-level version property is defined by the Compose Specification for backward compatibility. It is only informative.

I have also tested this with docker version 5:20.10.24~3-0~ubuntu-jammy and it works fine