all_resolutions_inference function broken with newer MNE versions

[john-veillette]

Unit tests are currently failing with:

=========================== short test summary info ============================
FAILED mne_ari/tests/test_ari.py::test_ari - TypeError: _cluster_indices_to_mask() missing 1 required positional argument: 'slice_out'
=================== 1 failed, 2 passed in 158.83s (0:02:38) ====================

The slice_out argument was added to _cluster_indices_to_mask in MNE (pull #12609).

In any event, I hope to fix this for a minor release soon, but in the meantime I believe this should only effect users with MNE versions greater than 1.6.