[Bug] CentOS 6 run spleeter version 2.0-2.3 process does't exit

- [ ] I didn't find a similar issue already open.
- [ ] I read the documentation (README AND Wiki)
- [ ] I have installed FFMpeg
- [ ] My problem is related to Spleeter only, not a derivative product (such as Webapplication, or GUI provided by others)

## Description
Installing spleeter by using conda on CentOS release 6.3 (Final). Then run the CMD: spleeter separate -p spleeter:2stems -o output test.mp3
spleeter process doesn't exit or report any thing.

Top shows it consumes CPU and memory:

## Step to reproduce

1. Installed using `conda`
2. Run as `spleeter separate -p spleeter:2stems -o output test.mp3`
3. Got `nothing` error

## Output

```bash
Share what your terminal says when you run the script (as well as what you would expect).
```
nothing
## Environment

| | |
| ----------------- | ------------------------------- |
| OS | Linux |
| Installation type | Conda |
| Hardware spec |CPU |

## Additional context

Start by reproducing `spleeter separate -p spleeter:2stems -o output test.mp3` in the reported Conda environment on CentOS 6.3, checking the terminal output and CPU or memory behavior. Done means the command either completes separation and exits or reports a clear actionable error instead of consuming resources without output.

Written by the indexing model from the issue text.