Add `str` for Issue

[kjaymiller]

When referencing the issue as a string display the syntax

f"#{Issue._number} - {Issue.title[:25]} by {Issue._owner['login']}"

[probro27]

Hi @kjaymiller , I can take this up. Please assign me this issue :))

[kjaymiller]

Happy to have you helping! Let me know if you need any help getting the tests figured out.