Bump actions/upload-artifact from 4 to 6 (#830)

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

.github/workflows/build-macos-x64.yml

@@ -47,13 +47,13 @@ jobs:
         mv Supersonic.zip Supersonic_HighSierra+.zip
 
     - name: Upload Big Sur+ package
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: Supersonic_mac_x64_BigSur+.zip
         path: Supersonic_BigSur+.zip
 
     - name: Upload High Sierra+ package
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: Supersonic_mac_x64_HighSierra+.zip
         path: Supersonic_HighSierra+.zip