ci: improve GitHub Actions workflow reliability

- Add `continue-on-error: true` to the GitHub Actions workflow

Signed-off-by: appleboy <appleboy.tw@gmail.com>

.github/workflows/main.yml

@@ -501,6 +501,7 @@ jobs:
 
       - name: testing ipv6
         uses: ./
+        continue-on-error: true
         with:
           host: 2402:1f00:8000:800::2628
           username: ubuntu