Bug: Stringzillas module is missing the attribute '__capabilities__'

### Describe the bug

Several tests fail like this:
```
=============================================================================== ERRORS ===============================================================================
________________________________________________________________ ERROR collecting test/szs_helpers.py ________________________________________________________________
szs_helpers.py:12: in
DEVICE_NAMES = ["default", "cpu_cores", "gpu_device"] if "cuda" in szs.__capabilities__ else ["default", "cpu_cores"]
^^^^^^^^^^^^^^^^^^^^
E AttributeError: module 'stringzillas' has no attribute '__capabilities__'
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
========================================================================== 1 error in 0.35s ==========================================================================
```

Version: 5.1.2
Python-3.12
FreeBSD 15.1

### Steps to reproduce

test

### Expected behavior

n/a

### StringZilla version

5.1.2

### Operating System

FreeBSD 15.1

### Hardware architecture

x86

### Which interface are you using?

C implementation

### Contact Details

_No response_

### Are you open to being tagged as a contributor?

- [ ] I am open to being mentioned in the project `.git` history as a contributor

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

Start by running the Python tests and inspecting test/szs_helpers.py, where collection reads szs.__capabilities__. Trace how the Python module exposes attributes in the C implementation; done means the attribute is available and the affected tests collect without the reported AttributeError.

Written by the indexing model from the issue text.