Update test.yml

.github/workflows/test.yml

@@ -49,7 +49,7 @@ jobs:
         docker logs -f "${{ job.services.db2.id }}" 2>&1 | grep -m 1 '(*) Setup has completed.'
 
     - name: Run tests
-      run: poetry run tox --parallel 4
+      run: poetry run tox --parallel 2
 
     - name: Build wheels
       run: poetry build