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] <[email protected]>

.github/workflows/ppx-push.yaml

@@ -57,7 +57,7 @@ jobs:
           ref: ${{ github.ref }}
 
       - name: Download Artifacts
-        uses: actions/download-artifact@v2
+        uses: actions/download-artifact@v4.1.7
 
       - name: Move / Rename Artifacts
         run: |