Bump actions/download-artifact from 2 to 4 in /.github/workflows (#495)

* 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>

* all up/download-artifact to v4

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Ed J <mohawk2@users.noreply.github.com>

.github/workflows/downstream-testing.yml

@@ -20,7 +20,7 @@ jobs:
           path: .github/devops
       - run: make -C .github/devops/docker -f Makefile.docker docker.pdl PATH_TO_PDL=$(pwd)
       - run: docker save pdl:latest --output pdl-latest.tar
-      - uses: actions/upload-artifact@v2
+      - uses: actions/upload-artifact@v4
         with:
           name: pdl-latest-image
           path: pdl-latest.tar
@@ -37,7 +37,7 @@ jobs:
       fail-fast: false
       matrix: ${{ fromJSON(needs.build-docker.outputs.project-matrix) }}
     steps:
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4
         with:
           name: pdl-latest-image
           path: .