Add tests for pass through calls of scanpy functions

[eroell]

Description of feature

We are right now not testing the pass through calls of scanpy functions work smoothly. As we are using the public scanpy API and watch scanpy closely, I don't expect this to cause a lot of troubles.

Nonetheless it would be great to check during CI that this remains the case I think - else these functions are hardly covered during testing.

E.g. we could check

from types import MappingProxyType
from unittest.mock import patch

import ehrapy as ep  # import your_pass_through_function


def test_pass_through_function(adata_mini):
    with patch("scanpy.pp.neighbors") as mock_scanpy_neighbors:

        ep.pp.neighbors(adata_mini)

        mock_scanpy_neighbors.assert_called_once_with(
            adata=adata_mini,
            n_neighbors=15,
            n_pcs=None,
            use_rep=None,
            knn=True,
            random_state=0,
            method="umap",
            transformer=None,
            metric="euclidean",
            metric_kwds=MappingProxyType({}),
            key_added=None,
            copy=False
            )

Thoughts @Zethson?