Fix: Support custom models for schedule monitor

[doubleoh13]

Description

This Pull Request addresses the issue where the package is tightly coupled with Spatie\ScheduleMonitor\Models\MonitoredScheduledTask and Spatie\ScheduleMonitor\Models\MonitoredScheduledTaskLogItem. While the spatie/laravel-schedule-monitor package allows users to specify custom models for these tables via configuration, the package currently fails to respect those configurations and continues to use the default models.

Problem

When custom models are specified in the config/schedule-monitor.php file, the package does not switch to using the configured models. This leads to errors when different table names are used.

Solution

This fix modifies the package to use the custom models specified in the configuration file for MonitoredScheduledTask and MonitoredScheduledTaskLogItem.
All references to the default models have been replaced with dynamic lookups, ensuring that custom models will be used if defined in the config.
Impact
This change ensures that users with custom models or table structures for scheduled tasks can still use the package without issues.