Re-opening a synced issue in Linear should re-open it in Github

[janbaykara]

Steps to reproduce:

1. Create a Github issue, see that it is synced to Linear
2. Close the synced Linear issue, see that the related Github issue has also closed
3. Change the synced Linear issue status back to "to do", see that the related Github issue remains closed

[jtormey]

Thank you! The behavior right now may "unlink" issues after it has been closed, I'll look to correct this.