fix: Use `.zip` in archive path

[dnys1]

Fixes https://github.com/dart-lang/setup-dart/issues/118

Ensures that downloads of the Dart SDK zip file carry the .zip extension so that subsequent calls to Expand-Archive on Windows succeed.

Notes

• The diff of index.mjs is quite large. I believe this is due to the version of Node I'm using (20.7.0). Happy to use a different version to keep the diff small, but wasn't sure which one is currently used. This could be noted in package.json (under engines), if desired, to ensure alignment with external contributions.

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[mit-mit]

Thanks @dnys1! Would you mind resolving conflicts? Then we'll take a look.

[dnys1]

@mit-mit Done 😄

[ntkme]

I'm blocked by this issue. I don't have access to directly contribute to this PR, so I opt to take the commits from this PR, and created a new PR with one more additional commit to fix the build issue: https://github.com/dart-lang/setup-dart/pull/134

[dnys1]

Thanks @ntkme I hadn't seen the build failure. I've pushed a new commit which runs the formatter, rebuilds, and signs the JS using npm run all on Dart 3.4.1.

[ntkme]

@dnys1 Thanks for the update. @devoncarew Can you please take another look and see if we can get this merged?

[kevmoo]

I'll leave for @devoncarew to hit the merge button!

[devoncarew]

Thanks for the contribution!