Disable integration test on GitHub Actions

Author: mrkn

.github/workflows/ci.yml

@@ -78,7 +78,7 @@ jobs:
       run: |
         for adapter in $ADAPTERS; do
           export IRUBY_TEST_SESSION_ADAPTER_NAME=$adapter
-          bundle exec rake test TESTOPTS=-v
+          bundle exec rake test TESTOPTS="-v -x integration"
         done
 
   windows: