fix string-based test

tests.py

@@ -34,7 +34,7 @@ def test_run_method(tmp_path):
 
     with mod.os_chdir(str(tmp_path)):
         # ensure single string command works
-        assert run(("ls -l")).returncode == 0
+        assert run(("ls -l"), shell=True).returncode == 0
         # test spaces are handled correctly:
         assert run(["touch", "file1 file2"]).returncode == 0
         assert os.path.exists("file1")