Fix app context error

[archang31]

Small change to fix the app context error:

ctfd-1 | ERROR [apscheduler.executors.default] Job "ContainerManager.wrapper_run_command (trigger: interval[0:00:05], next run at: 2025-11-09 14:01:28 UTC)" raised an exception 
ctfd-1 | Traceback (most recent call last): 
ctfd-1 | File "/opt/venv/lib/python3.11/site-packages/apscheduler/executors/base.py", line 131, in run_job ctfd-1 | retval = job.func(*job.args, **job.kwargs) 
ctfd-1 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
ctfd-1 | File "/opt/CTFd/CTFd/plugins/containers/container_manager.py", line 127, in wrapper_run_command 
ctfd-1 | return func(self, *args, **kwargs) ctfd-1 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ 
ctfd-1 | File "/opt/CTFd/CTFd/plugins/containers/container_manager.py", line 146, in kill_expired_containers 
ctfd-1 | with app.app_context(): 
ctfd-1 | ^^^^^^^^^^^^^^^^^ 
ctfd-1 | TypeError: Flask.app_context() missing 1 required positional argument: 'self'