Leave a comment when reopening issue

Summary

Leaves a comment on a reopened issue with a link to the pipeline that reopened it.

Closes #18 (closed)

Testing

1. Pushed https://gitlab.com/mnielsen/issue-bot-examples/-/commit/6ec806cc9e262f00e235b5781a432b71df784622
2. Pipeline ran: https://gitlab.com/mnielsen/issue-bot-examples/-/pipelines/517288010
3. Issue created: https://gitlab.com/mnielsen/issue-bot-examples/-/issues/28
4. Manually closed issue
5. Re-ran the issue-bot job: https://gitlab.com/mnielsen/issue-bot-examples/-/jobs/2338508576
6. Comment added: https://gitlab.com/mnielsen/issue-bot-examples/-/issues/28#note_913506872
7. Re-ran the issue-bot job: https://gitlab.com/mnielsen/issue-bot-examples/-/jobs/2338510515
8. No comment added (expected): https://gitlab.com/mnielsen/issue-bot-examples/-/jobs/2338510515
9. Manually closed issue
10. Re-ran the issue-bot job: https://gitlab.com/mnielsen/issue-bot-examples/-/jobs/2338513641
11. Comment added: https://gitlab.com/mnielsen/issue-bot-examples/-/issues/28#note_913507625