Make artifact names unique for each CI run

Author: ianthomas23

.github/workflows/main.yml

@@ -123,7 +123,7 @@ jobs:
         if: always() && matrix.os == 'ubuntu'
         uses: actions/upload-artifact@v4
         with:
-          name: ui-test-output
+          name: ui-test-output-${{ matrix.os }}-${{ matrix.python }}-${{ matrix.mpl-version }}
           path: |
             ui-tests/playwright-report
             ui-tests/test-results