Add support for free space threshold setting

[rfsbraz]

No description provided.

[flamflumbo]

Would this feature support mergerfs combined storage? I having an issue with media_cleaner.py trying to find the folder ( which im assuming is the mount point for the mergerfs folder?

2024-09-30 03:47:08 - INFO :: deleterr.py :: deleterr : Running version rfsbraz/deleterr:0.0.19
2024-09-30 03:47:08 - INFO :: deleterr.py :: deleterr : Log level set to INFO
2024-09-30 03:47:08 - INFO :: deleterr.py :: deleterr : Processing sonarr instance: 'sonarr'
2024-09-30 03:47:09 - ERROR :: media_cleaner.py :: deleterr : Could not find folder '/media/storage' in server instance. Skipping library 'TV Shows'
2024-09-30 03:47:09 - INFO :: deleterr.py :: deleterr : Freed 0.00 B of space by deleting shows
2024-09-30 03:47:09 - INFO :: deleterr.py :: deleterr : Processing radarr instance: 'Radarr'
2024-09-30 03:47:09 - ERROR :: media_cleaner.py :: deleterr : Could not find folder '/media/storage' in server instance. Skipping library 'Movies'
2024-09-30 03:47:09 - INFO :: deleterr.py :: deleterr : Freed 0.00 B of space by deleting movies