Bump actions/download-artifact from 3 to 4

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 3 to 4.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v3...v4)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/build-test-measure.yml

@@ -639,13 +639,13 @@ jobs:
       prod-checksum: ${{ steps.output-checksums.outputs.prod-checksum }}
     steps:
       - name: Download dev build
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: amp-${{ needs.build-zip.outputs.branch-name }}-${{ needs.build-zip.outputs.git-sha-8 }}-dev
           path: builds/dev
 
       - name: Download prod build
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: amp-${{ needs.build-zip.outputs.branch-name }}-${{ needs.build-zip.outputs.git-sha-8 }}-prod
           path: builds/prod