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/ci.yml

@@ -297,7 +297,7 @@ jobs:
 
       # Verify that the sample projects can compile after switching to NuGet references
       - name: Download NuGet package artifact
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: nuget-packages
           path: local-nuget-packages
@@ -353,7 +353,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Download NuGet package artifact
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: nuget-packages
       - name: Publish to FeedzIO
@@ -371,11 +371,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Download NuGet package artifact
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: nuget-packages
       - name: Download Samples artifact
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: samples