Merge downstream tests fail for PR authors who are not org members

[dprotaso]

cc @shinigambit looks like there's an issue with the merge upstream step in the action for non-members of the org?

Originally posted by @dprotaso in knative/pkg#2390 (comment)

[dprotaso]

/assign @shinigambit @kvmware

[dprotaso]

Another instance knative/pkg#2425

[github-actions]

This issue is stale because it has been open for 90 days with no
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inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[dprotaso]

/lifecycle frozen

note the downstream workflow yaml is in knative/actions repo