Bump the artifacts group with 2 updates

Bumps the artifacts group with 2 updates: [actions/upload-artifact](https://github.com/actions/upload-artifact) and [actions/download-artifact](https://github.com/actions/download-artifact).


Updates `actions/upload-artifact` from 5 to 6
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/compare/v5...v6)

Updates `actions/download-artifact` from 6 to 7
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](https://github.com/actions/download-artifact/compare/v6...v7)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: artifacts
- dependency-name: actions/download-artifact
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: artifacts
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/tarball.yml

@@ -39,7 +39,7 @@ jobs:
         make tarball
 
     - name: Upload tarball
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
         name: tarball-${{ matrix.go-version }}
         path: nextcloud-spreed-signaling*.tar.gz
@@ -58,7 +58,7 @@ jobs:
         go-version: ${{ matrix.go-version }}
 
     - name: Download tarball
-      uses: actions/download-artifact@v6
+      uses: actions/download-artifact@v7
       with:
         name: tarball-${{ matrix.go-version }}
 
@@ -103,7 +103,7 @@ jobs:
         go-version: ${{ matrix.go-version }}
 
     - name: Download tarball
-      uses: actions/download-artifact@v6
+      uses: actions/download-artifact@v7
       with:
         name: tarball-${{ matrix.go-version }}