ci/test-nginx: show mock-sentry logs (#1816)

Author: alxndrsn

.github/workflows/test.yml

@@ -59,6 +59,8 @@ jobs:
       run: cd test/nginx && docker compose -f nginx.test.docker-compose.yml logs --no-log-prefix service
     - if: always()
       run: cd test/nginx && docker compose -f nginx.test.docker-compose.yml logs --no-log-prefix enketo
+    - if: always()
+      run: cd test/nginx && docker compose -f nginx.test.docker-compose.yml logs --no-log-prefix sentry-mock
   test-secrets:
     timeout-minutes: 2
     runs-on: ubuntu-latest