Adjust tests workflow for fork PRs

[max-ostapenko]

• [x] changed tests workflow to pull_request_target trigger

Potential vulnerabilities:

• stolen secrets.

[max-ostapenko]

@tunetheweb, I did minimal changes (hope I understood you correct) And existing PRs need to rebase in order to use a new workflow.

[tunetheweb]

Any ideas why it didn’t kick off a run for this PR?

[max-ostapenko]

I think it's because it will run once merged (source) Could replicate it in a test repo.

P.S. Seems to be a good idea to avoid config conflicts/issues when running non-verified workflows on a non-verified code.