fix: propagate exit code (#108)

* fix(pytest): propagate exit code

* feat: derive exit code for unittest

neotest.py

@@ -17,4 +17,4 @@ with add_to_path():
     from neotest_python import main
 
 if __name__ == "__main__":
-    main(sys.argv[1:])
+    sys.exit(main(sys.argv[1:]))