Token field does not support fine-grained tokens format

[rodmatos]

The HTML input seems to include validation for GitHub's Personal Access Tokens (PATs). GitHub has introduced fine-grained PATs, which have a different format.

To provide the users of the extension a bit more fine-grained control over the PATs, it would be beneficial to introduce support for those.

[notlmn]

PRs welcome.

[mgrobaker]

is this as simple as changing the HTML validation in the field? will the extension then work with fine-grained tokens?
If so then I can make the change to the front end
cc @sindresorhus