fix(ci): enable forks to run netsim manually (#1834)

## Description

Should close #1832

## Notes & open questions

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## Change checklist

- [ ] Self-review.
- [ ] Documentation updates if relevant.
- [ ] Tests if relevant.

.github/workflows/netsim.yml

@@ -44,6 +44,7 @@ jobs:
       if: github.event_name == 'issue_comment'
       uses: actions/checkout@master
       with:
+        repository: ${{ github.event.issue.repository.full_name }}
         submodules: recursive
         ref: ${{ steps.refs.outputs.head_ref }}