personal access token should only use public_repo scope by default

Thanks for such a nice project!

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From the security perspective, I think it had better to check only public_repo access by default when we click the Generate One link.

I in this case, we can replace the following link:

- https://github.com/settings/tokens/new?scopes=repo&description=GitHub%20Issue%20Link%20Status
+ https://github.com/settings/tokens/new?scopes=public_repo&description=GitHub%20Issue%20Link%20Status

Also, It's worth to mention if someone wants to use this extension in the private repositories, we can mention that by saying something like: "To use this extension in the private repositories, consider give repo scope to use."

Wdyt?