replace test input sep_mult -> separate_multiplicative for aesthetic reasons

validphys2/src/validphys/tests/test_pseudodata.py

@@ -75,7 +75,7 @@ def test_no_savepseudodata():
 
 def test_read_matches_recreate():
     reads = API.read_fit_pseudodata(fit=PSEUDODATA_FIT)
-    recreates = API.recreate_fit_pseudodata(fit=PSEUDODATA_FIT, sep_mult=True)
+    recreates = API.recreate_fit_pseudodata(fit=PSEUDODATA_FIT, separate_multiplicative=True)
     for read, recreate in zip(reads, recreates):
         # We ignore the absolute ordering of the dataframes and just check
         # that they contain identical elements.