Handle forks and secrets politely

[jsoref]

The current behavior of this plugin is very hostile to forks.

This is what I was trying to add to a workflow so that it wouldn't waste slots and resources on my forks:
jsoref/zio-http@0309bf2

It doesn't work because this plugin also screams if the workflow is out of sync. So, please kindly add something functionally equivalent to the above commit so that when users do work (both pushes and pull requests) in forks and they don't have the secrets that the root of the fork network has, the workflow won't hang for hours before dying.