build(deps): bump actions/upload-artifact from 3 to 4

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 3 to 4.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/compare/v3...v4)

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

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

.github/workflows/sphinx-tuttest.yml

@@ -75,12 +75,12 @@ jobs:
       - name: Build examples
         run: bash .github/scripts/build-examples.sh ${{matrix.fpga-fam}} ${{matrix.example}}
 
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: ${{matrix.os}}-${{matrix.os-version}}-f4pga-examples-bitstreams-${{ matrix.name }}
           path: '**/*.bit'
 
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: f4pga-examples-plots-${{ matrix.name }}
           path: '**/plot_*.svg'