style: ruff format tests/test_package_exports.py

CI's QA → Python Isolation → Check formatting step failed on this file.
Phase C subagent added the export test but didn't run the formatter
afterward. One-line whitespace fix.

Author: NeuralEmpowerment

lib/python/agentic_isolation/tests/test_package_exports.py

@@ -116,4 +116,5 @@ def test_observability_event_has_subagent_fields(self) -> None:
 
 def test_workspace_files_exported():
     import agentic_isolation
+
     assert hasattr(agentic_isolation, "WorkspaceFiles")