fix: Use .zip in archive path (#119)

* fix: Use `.zip` in archive path

Fixes #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` to ensure alignment with external contributions.

* Update link

* Update changelog

* Reformat and sign w/ Dart 3.4.1

CHANGELOG.md

@@ -1,3 +1,9 @@
+## v1.6.5-wip
+
+- Fix zip path handling on Windows 11 ([#118][])
+
+[#118]: https://github.com/dart-lang/setup-dart/issues/118
+
 ## v1.6.4
 
 * Rebuild JS code.