fix yet another pandas deprecation

evcouplings/compare/distances.py

@@ -770,7 +770,7 @@ def _get_col_name(col_name):
             # extract coverage segments for all individual structures
             segments = {
                 _get_col_name(col_name): find_segments(series.dropna().sort_index().index)
-                for col_name, series in coverage_cols.iteritems()
+                for col_name, series in coverage_cols.items()
             }
 
             return segments