Bump actions/upload-artifact from 4 to 6 (#404)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4...v6)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Shane Krueger <shane@acdmail.com>

Author: dependabot[bot]

.github/workflows/publish-preview.yml

@@ -41,7 +41,7 @@ jobs:
         working-directory: src
         run: dotnet pack --no-restore -c Release -p:VersionSuffix=$GITHUB_RUN_NUMBER -o out
       - name: Upload artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: Nuget packages
           path: |

.github/workflows/publish-release.yml

@@ -47,7 +47,7 @@ jobs:
         working-directory: src
         run: dotnet pack --no-restore --no-build -c Release -p:Version=$version -o out
       - name: Upload Nuget packages as workflow artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: Nuget packages
           path: |