github/workflows: Print test failures for webassembly workflow.

Signed-off-by: Damien George <damien@micropython.org>

.github/workflows/ports_webassembly.yml

@@ -22,3 +22,6 @@ jobs:
       run: source tools/ci.sh && ci_webassembly_build
     - name: Run tests
       run: source tools/ci.sh && ci_webassembly_run_tests
+    - name: Print failures
+      if: failure()
+      run: tests/run-tests.py --print-failures