Fix snapshot restore does not work after export/import of project

gns3server/controller/snapshot.py

@@ -139,7 +139,7 @@ class Snapshot:
             # delete the current project files
             project_files_path = os.path.join(self._project.path, "project-files")
             if os.path.exists(project_files_path):
-                await wait_run_in_executor(shutil.rmtree, project_files_path)
+                await wait_run_in_executor(shutil.rmtree, project_files_path, ignore_errors=True)
             with open(self._path, "rb") as f:
                 project = await import_project(
                     self._project.controller,