Bump actions/upload-artifact from 5 to 6

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v5...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] <[email protected]>

Author: dependabot[bot]

.github/workflows/build-deb.yml

@@ -43,7 +43,7 @@ jobs:
       run: bash package-build/build-package.sh $(pwd)
 
     - name: "Upload deb-packages"
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
         name: artifact-deb
         path: ./*.deb

.github/workflows/build-nuget.yml

@@ -98,7 +98,7 @@ jobs:
       run: nuget push "$env:GITHUB_WORKSPACE\*.nupkg" $env:NUGET_API_KEY -Source https://api.nuget.org/v3/index.json
 
     - name: Upload built .nupkg as workflow artefact
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
         name: artifact-nuget
         path: '*.nupkg'