chore(deps): bump actions/setup-node from 4 to 7 (#1285)

* chore(deps): bump actions/setup-node from 4 to 7

Bumps [actions/setup-node](https://github.com/actions/setup-node) from 4 to 7.
- [Release notes](https://github.com/actions/setup-node/releases)
- [Commits](https://github.com/actions/setup-node/compare/v4...v7)

---
updated-dependencies:
- dependency-name: actions/setup-node
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

* chore(ci): allow actions/setup-node v7 in the Snap workflow policy

The Snap supply-chain policy test pins the exact major of every action
the build workflow may use, so bumping actions/setup-node in the
workflow without updating BUILD_ACTION_ALLOWLIST fails
publish-snap-workflow.test.mjs.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: 4gray <serega05@gmail.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

tools/packaging/snap-workflow-policy.test-helpers.mjs

@@ -18,7 +18,7 @@ const BUILD_ACTION_ALLOWLIST = Object.freeze([
     'actions/cache@v6',
     'actions/checkout@v7',
     'actions/download-artifact@v8',
-    'actions/setup-node@v4',
+    'actions/setup-node@v7',
     'actions/upload-artifact@v7',
     'pnpm/action-setup@v4',
     'softprops/action-gh-release@v2',