Fix argsort inside numba.jit using kind='mergesort' (#1176)

* Fix argsort inside numba.jit using kind='mergesort'

See https://numba.readthedocs.io/en/stable/reference/numpysupported.html#other-methods

* Bump merged_s2s version

* Provide `sort_kind` as an argument of get_merge_instructions

straxen/plugins/merged_s2s/merged_s2s.py

@@ -15,7 +15,7 @@ class MergedS2s(strax.OverlapWindowPlugin):
     Merge together peaklets if peak finding favours that they would
     form a single peak instead.
     """
-    __version__ = '1.0.0'
+    __version__ = '1.0.1'
 
     depends_on = ('peaklets', 'peaklet_classification', 'lone_hits')
     data_kind = 'merged_s2s'
@@ -133,7 +133,8 @@ def compute(self, peaklets, lone_hits):
     @numba.njit(cache=True, nogil=True)
     def get_merge_instructions(
             peaklet_starts, peaklet_ends, areas, types,
-            gap_thresholds, max_duration, max_gap, max_area):
+            gap_thresholds, max_duration, max_gap, max_area,
+            sort_kind='mergesort'):
         """
         Finding the group of peaklets to merge. To do this start with the
         smallest gaps and keep merging until the new, merged S2 has such a
@@ -149,7 +150,7 @@ def get_merge_instructions(
         peaklet_start_index = np.arange(len(peaklet_starts))
         peaklet_end_index = np.arange(len(peaklet_starts))
 
-        for gap_i in np.argsort(peaklet_gaps):
+        for gap_i in np.argsort(peaklet_gaps, kind=sort_kind):
             start_idx = peaklet_start_index[gap_i]
             inclusive_end_idx = peaklet_end_index[gap_i + 1]
             sum_area = np.sum(areas[start_idx:inclusive_end_idx + 1])