Enable path debug in filesystem error messages (#93)

Before:

```
failed to open file `file.txt`: The system cannot find the file specified. (os error 2)
```

After (with `debug` feature):

```
failed to open file `file.txt`: The system cannot find the file specified. (os error 2)

Path does not exist `file.txt`
- Absolute path `/path/to/dir/file.txt`
- Missing `file.txt` from parent directory:
  `/path/to/dir`
    └── `file.md`
    └── `different.txt`
```

Author: schneems

Cargo.lock

@@ -15,7 +15,7 @@ bullet_stream = "0.11"
 chrono = {version = "0.4", features = ["serde"] }
 clap = { version = "4.5", features = ["derive"] }
 flate2 = "1"
-fs-err = "3"
+fs-err = { version = "3", features = ["debug"] }
 fs2 = "0.4"
 fun_run = "0.6"
 gem_version = "0.3"