Bump actions/download-artifact from 2 to 4.1.7 in /.github/workflows

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 2 to 4.1.7.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v2...v4.1.7)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-type: direct:production
...

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

.github/workflows/build.yml

@@ -54,15 +54,15 @@ jobs:
         binary: [unabto_tunnel]
     if: github.event_name == 'release' && success()
     steps:
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4.1.7
         with:
           name: artifacts_ubuntu-22.04
           path: linux
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4.1.7
         with:
           name: artifacts_windows-2022
           path: windows
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4.1.7
         with:
           name: artifacts_macos-12
           path: macos