[DOCS] Skip docs deploy on forks

[jbampton]

https://docs.github.com/en/actions/using-jobs/using-conditions-to-control-job-execution#example-only-run-job-for-specific-repository

Did you read the Contributor Guide?

• Yes, I have read the Contributor Rules and Contributor Development Guide

Is this PR related to a JIRA ticket?

• No, this is a documentation update. The PR name follows the format [DOCS] my subject.

What changes were proposed in this PR?

When a contributor syncs their fork from the upstream and pushes back to origin master on GitHub the docs build currently fails as seen in the next two links:

https://github.com/jbampton/sedona/actions/runs/8780798846/job/24091461356

https://github.com/furqaankhan/sedona/actions/runs/8725430958/job/23938384642

How was this patch tested?

Here is an image of the failure:

Probably the worst part about this bug is that you get sent out an email from GitHub about the failing Docs build.

Just extra email spam like this:

Did this PR include necessary documentation updates?

• No, this PR does not affect any public API so no need to change the documentation.