Github Actions: do not run publish_head.yml in forks

[zerospiel]

If a repository is forked then the deploy-docs job from the publich_head.yml has not to be run because at least it will trigger the error caused by the git fetch origin gh-pages from the job's last step.

Expected:
In a fork I expect to perform git checkout main && git fetch --all -p && git rebase upstream/main && git push to successfully run without any failure in actions.

Actual:
Performing the aforementioned command triggers the deploy-docs job and causes failure which ends up with redundant frictions/e-mail notifications/etc.

[PrashantR30]

Hello @DinaBelova Please assign it to me. Thanks.