The cached files aren't being removed after the stale duration is over!

## 🐛 The cached files aren't being removed after the stale duration is over!

With Custom Cache Manager, the stale duration isn't working! It's not removing the file after the stale duration is over. I had set the stale duration to 3 minutes, but the file was deleted even after more than 30 hours.

### Expected behavior
The cached files are supposed to be deleted after the stale duration of the file is over. But, the file continues to remain in the cache ruining the whole structure.

### Reproduction steps
Just cache a file with Custom Cache Manager, for DefaultCacheManager doesn't come with a stale duration option, and assign Stale Duration to anything, i assigned it 3 minutes to test it more efficiently. Then, I just invoked my function to see if the file is cached without displaying it, which I was doing with Cached_network_Image. I used the getFileFromCache function to get the file specifically and only from the cache, and it printed that the cached file exists, even after the day since is caching. Btw, remember I cached it for 3 minutes.

### Configuration

**Version:** flutter_cache_manager: ^3.3.1

**Platform:**
- [ ] :iphone: iOS
- [ ] :robot: Android

Reproduce the issue with Custom Cache Manager using a three-minute stale duration, then call getFileFromCache after the duration has elapsed. Done means the cached file is removed or is no longer returned from the cache; the issue does not name a source file or test to inspect.

索引モデルが issue の本文から書いたものです。