[3.12] gh-143930: Reject leading dashes in webbrowser URLs

[Pinky-Chaudhary]

(cherry picked from commit 82a24a4)

• Issue: Reject leading dashes in webbrowser.open() #143930

[ambv]

The backport needs to be equivalent to what was landed in 3.13 - 3.15. Don't make any other changes.

[bedevere-app]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[python-cla-bot]

All commit authors signed the Contributor License Agreement.

[Pinky-Chaudhary]

I have made the requested changes; please review again

[bedevere-app]

Thanks for making the requested changes!

@ambv: please review the changes made to this pull request.

[ambv]

Thanks, @Pinky-Chaudhary!