Updated the Node version to version 12
Antora 2.3.x states that you should be using Node version 12 with Antora, but the antora/antora:2.3.4
docker image was still based on Node 10.
This merge requests bumps the Node version to 12.
The 17.0 major release is coming on May 16, 2024! This version brings many exciting improvements to GitLab, but also removes some deprecated features. We are introducing three breaking change windows during which we expect breaking changes to be deployed to GitLab.com. You can read more about it on our blogpost. The second breaking change window begins 2024-04-29 09:00 UTC and ends 2024-05-01 22:00 UTC.
Antora 2.3.x states that you should be using Node version 12 with Antora, but the antora/antora:2.3.4
docker image was still based on Node 10.
This merge requests bumps the Node version to 12.