fix: trigger legacy tasks manager every 5m (#2987)

### Description

This ensures that when the LibreTime interface is not used for a long
time, we still have the task manager run essential tasks for the
schedule.

Related to #2670

worker/libretime_worker/tasks.py

@@ -9,7 +9,9 @@ from urllib.parse import urlsplit
 import mutagen
 import requests
 from celery import Celery, signals
+from celery.schedules import crontab
 from celery.utils.log import get_task_logger
+from libretime_api_client.v1 import ApiClient as LegacyClient
 from mutagen import MutagenError
 from requests import RequestException, Response
 
@@ -19,6 +21,11 @@ from .config import config
 worker = Celery()
 logger = get_task_logger(__name__)
 
+legacy_client = LegacyClient(
+    base_url=config.general.public_url,
+    api_key=config.general.api_key,
+)
+
 
 @signals.worker_init.connect
 def init_sentry(**_kwargs):
@@ -37,6 +44,22 @@ def init_sentry(**_kwargs):
         )
 
 
+worker.conf.beat_schedule = {
+    "legacy-trigger-task-manager": {
+        "task": "libretime_worker.tasks.legacy_trigger_task_manager",
+        "schedule": crontab(minute="*/5"),
+    },
+}
+
+
+@worker.task()
+def legacy_trigger_task_manager():
+    """
+    Trigger the legacy task manager to perform background tasks.
+    """
+    legacy_client.trigger_task_manager()
+
+
 @worker.task(name="podcast-download", acks_late=True)
 def podcast_download(
     episode_id: int,