ci(dependabot): bump actions/upload-artifact from 4 to 6 (#439)

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>

Author: dependabot[bot]

.github/workflows/analyze.yml

@@ -27,7 +27,7 @@ jobs:
             - name: Run analysis code
               run: uv run analyze -r cellpack/tests/recipes/v2/test_spheres.json -a cellpack/tests/analysis-configs/PR_analysis_config.json -p cellpack/tests/outputs/test_spheres/spheresSST
             - name: Upload results
-              uses: actions/upload-artifact@v4
+              uses: actions/upload-artifact@v6
               with:
                   name: results
                   path: cellpack/tests/outputs/test_spheres/

.github/workflows/make-requirements.yml

@@ -56,7 +56,7 @@ jobs:
           esac
 
       - name: Upload requirements files
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: ${{ steps.platform.outputs.platform }}-requirements
           path: requirements/${{ steps.platform.outputs.platform }}