feat: Update Episcanner-Downloader DAG with Improved PSQL Connection and Schedule

[esloch]

This pull request updates the Episcanner-Downloader DAG. The following changes have been made:

• Improved type hints and docstrings for better code readability and maintainability.
• Set variables for establishing a connection between Episcanner and PostgreSQL database, allowing seamless data retrieval and storage.
• Updated the schedule to run the DAG every Sunday at 3 AM, ensuring timely and consistent data processing.
• Refactored the cloning of the repository and installation of Poetry, streamlining the process and enhancing efficiency.
• Renamed the task "set_variables_task" to "set_connection_variables" to reflect its purpose accurately.
• Updated the Dockerfile to include necessary dependencies and configurations for the Episcanner-Downloader APP.
• Set catchup to False to prevent backfilling of missed task instances.
• Modify the data source parameter to export data for all available sources.
• Add a task to remove the episcanner-downloader repository after data export.

[luabida]

When using the DAG context manager, it is not necessary to set the dag variable to the tasks

[luabida]

When using the DAG context manager, it is not necessary to set the dag variable to the tasks