Issue tracker check doesn't support certain kind of working URLs

[guidezpl]

Here, we link to an issue tracker with query parameters, which works fine, but pana reports an issue

https://pub.dev/packages/google_fonts/score

Provide a valid pubspec.yaml

Issue tracker URL doesn't exist.
At the time of the analysis https://github.com/material-foundation/flutter-packages/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+google_fonts%22 was unreachable. Make sure that the website is reachable via HEAD requests.

[isoos]

@guidezpl: We previously thought that it is an issue with rate limiting. This is an interesting angle, thanks for reporting it, we will investigate.

[guidezpl]

Actually, also found the query parameter-less URL for a different package also had issues https://pub.dev/packages/material_color_utilities/score

At the time of the analysis https://github.com/material-foundation/material-color-utilities/issues was unreachable

[barneysspeedshop]

From what I can tell, this is happening on ALL packages on pub.dev.
Steps to reproduce:

• publish any package with a valid issue tracker link
• wait for scoring to happen
• observed behavior: the package has a warning that the issue tracker was unreachable
• expected behavior: the package does not have a warning, and the issue tracker link is properly validated
  ** Alternative expected behavior: there is no scoring metric for this because it's unreliable

You can view any package on pub.dev to verify. Choose ANY "Flutter Favorite" package, those should be a "gold standard"
Each one has this warning.

Unauthenticated requests to github are limited to 60 requests per hour per IP address. Authenticated requests have a much higher limit of 5,000 requests per hour per user or app.