Unable to run Spleeter

## Description

I had this working and have used it many times in the past. I have a little script to make it easy to use spleeter. I tried to use it today and it broke stating:

```
Earth:splitmp3 Dreamgirl.mp3
Traceback (most recent call last):
File "/usr/local/bin/spleeter", line 5, in
from spleeter.__main__ import entrypoint
ModuleNotFoundError: No module named 'spleeter'
Earth:
``'
## Step to reproduce

1. Installed using a method I can't remember. I think I just cloned the repo. Now if I try pip install spleeter I get:

```
arth:pip install spleeter
error: externally-managed-environment

× This environment is externally managed
╰─> To install Python packages system-wide, try apt install
python3-xyz, where xyz is the package you are trying to
install.

If you wish to install a non-Debian-packaged Python package,
create a virtual environment using python3 -m venv path/to/venv.
Then use path/to/venv/bin/python and path/to/venv/bin/pip. Make
sure you have python3-full installed.

If you wish to install a non-Debian packaged Python application,
it may be easiest to use pipx install xyz, which will manage a
virtual environment for you. Make sure you have pipx installed.

See /usr/share/doc/python3.12/README.venv for more information.

note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
hint: See PEP 668 for the detailed specification.
Earth:
```
2. Run as my normal user
3. Got

Earth:spleeter separate -b 320k -c flac -f {instrument}.{codec} -p spleeter:5stems -o . Dreamgirl.mp3
Traceback (most recent call last):
File "/usr/local/bin/spleeter", line 5, in
from spleeter.__main__ import entrypoint
ModuleNotFoundError: No module named 'spleeter'
Earth:

## Output

See above

## Environment

| | |
| ----------------- | ------------------------------- |
| OS | Linux Ubuntu 24.04 |
| Installation type | Don't remember |
| RAM available | 16 gig |
| Hardware spec | System 76 Thelio - Nvidia GPUs but I don't think I'm using them |

## Additional context

As I said, this was working. Note I have a small spleeter Python script in /usr/local/bin:

```
#!/usr/bin/python3
# -*- coding: utf-8 -*-
import re
import sys
from spleeter.__main__ import entrypoint
if __name__ == '__main__':
sys.argv[0] = re.sub(r'(-script\.pyw|\.exe)?$', '', sys.argv[0])
sys.exit(entrypoint())
```