[Bug] pip install does not find latest version from pypi

## Description

`pip install spleeter` tries to install version `2.1.0`

It complains that no newer versions exist when you specify them, e.g. `pip install spleeter==2.4.0`

Meanwhile they seem to exist: https://pypi.org/project/spleeter/#history

## Step to reproduce

`pip install spleeter=2.4.0`

```
ERROR: Could not find a version that satisfies the requirement spleeter==2.4.0 (from versions: 2.1.0)
ERROR: No matching distribution found for spleeter==2.4.0
```

🤷