Update artifact name to include OS in buildtest workflow

Author: tg123

.github/workflows/buildtest.yaml

@@ -33,7 +33,7 @@ jobs:
       - name: Upload test results
         uses: actions/upload-artifact@v4
         with:
-          name: test-results
+          name: test-results-${{ matrix.os }}
           path: ./TestResults
         if: ${{ always() }} # Always run this step even on failure