Sporadical CI failures in `test_numba.py`

Failure:
```console
FAILED test/test_numba.py::test_integral[float32] - AttributeError: module 'poisson_numba' has no attribute 'form_poisson_a'
FAILED test/test_numba.py::test_expression[float32] - AttributeError: module 'poisson_numba' has no attribute 'expression_poisson_0'
```

Seems to be non-deterministic, rerunning pipelines results in a passing CI run.