ImportError: cannot import name CDM from pyHalo.preset_models (dependency/API mismatch)

## ImportError: cannot import name `CDM` from `pyHalo.preset_models` (dependency/API mismatch)

Hello maintainers,

While testing this repository on a clean **Windows** setup, I encountered a dependency/API mismatch that prevents running the **Model_I** simulation scripts.

### Description

Running `Model_I/sim_axion.py` fails during import with:

```text
ImportError: cannot import name 'CDM' from 'pyHalo.preset_models'
```

This happens before the script reaches execution, so it blocks cross-platform testing and reproducibility for new contributors.

### Steps to Reproduce

1. Clone the repository
2. Create and activate a virtual environment (Windows) and install dependencies:

```bash
py -3.11 -m venv .venv
.venv\Scripts\activate
pip install -r requirements.txt
pip install -e .
```

3. Run:

```bash
python Model_I/sim_axion.py
```

### Observed Behavior

The script fails with:

```text
ImportError: cannot import name 'CDM' from 'pyHalo.preset_models'
```

Environment:

* OS: Windows
* Python: 3.11

Installed `pyHalo` version:

```bash
python -c "import pyHalo; print(pyHalo.__version__)"
```

Output:

```text
0.2.8
```

Additional check:

```bash
python -c "import pyHalo.preset_models as pm; print([x for x in dir(pm) if 'CDM' in x])"
```

Output:

```text
[]
```

### Expected Behavior

The simulation scripts should run successfully after installation.
Alternatively, the repository should pin a compatible `pyHalo` version and/or update the import statement according to the correct `pyHalo` API.

Thank you!



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ImportError: cannot import name CDM from pyHalo.preset_models (dependency/API mismatch) #100