github actor is not dependabot when rerunning the job

[GersonTf]

I have an automerge workflow that checks the PR author:
if: ${{ github.event.workflow_run.conclusion == 'success' && github.actor == 'dependabot[bot]' }}
and gets triggered after the tests workflow:

name: Automerge Dependabot PRs
on:
  workflow_run:
    workflows: ["test"]
    types:
      - completed

The problem is that, sometimes, if the tests fail, the dependabot automerge doesn't get triggered (as expected) and the PR stays open. When I fix the test issue, I re-run the jobs and the dependabot one doesn't get triggered anymore saying that the author is not dependabot when it is.

EDIT: in a second check, I don't think it works either if the tests are success. I think the problem is linked with the workflow_run trigger not having dependabot as an actor even tho dependabot created the PR.

[GersonTf]

this is probably linked to #490