fix: do not delete the logs folder when the database is not empty

It can happen that the logs folder is empty (all jobs are pending) but the database is not empty. We should not delete the logs folder in this case.

src/gridtk/manager.py

@@ -203,6 +203,6 @@ def __del__(self):
                 and len(self.list_jobs(update_jobs=False)) == 0
             ):
                 Path(self.database).unlink()
-            if self.logs_dir.exists() and len(os.listdir(self.logs_dir)) == 0:
-                shutil.rmtree(self.logs_dir)
+                if self.logs_dir.exists() and len(os.listdir(self.logs_dir)) == 0:
+                    shutil.rmtree(self.logs_dir)
         self.engine.dispose()