corkscrew: replace WEBrick with TCPServer for test, update license

[timsutton]

• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

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• replace WEBrick with TCPServer (as suggested here)
• update license to GPL 2.0 to GPL-2.0-or-later

[request-info]

Please provide a better issue/pull request title and/or description!

[timsutton]

Basing this on https://github.com/patpadgett/corkscrew?tab=GPL-2.0-1-ov-file

[timsutton]

Relates to #162041 (comment)

[bevanjkay]

@timsutton I'm not sure we should be only running syntax here to make sure the tests pass on CI. But can add ci-no-bottles.

[timsutton]

@bevanjkay Ah, thank you for pointing that out! I didn't realize the label would cause it to skip tests, but I guess that makes sense. I'll remove the label then.