Fix database connections leakage (#980)

[rznzippy]

Description

This pull request addresses a database connection leak caused by django-apscheduler not closing stale connections after task execution. The solution involves wrapping run_with_process_lock with the @close_old_connections decorator provided by django-apscheduler.

For more details, refer to the django-apscheduler documentation on database connections and timeouts.

Changes

• Added @close_old_connections decorator to run_with_process_lock to ensure database connections are properly closed after each scheduled task.

Related Issue

• Fixes #980: Database connections not closed after scheduled tasks, leading to connection leakage.