fix the unit of retroen rule

Author: KEHANG

input/kinetics/families/Retroen/rules.py

@@ -10,7 +10,7 @@
     index = 1,
     label = "alkylaromatic",
     kinetics = ArrheniusEP(
-        A = (8.50e11, 'cm^3/(mol*s)'),
+        A = (8.50e11, 's^-1'),
         n = 0,
         alpha = 0,
         E0 = (54.40, 'kcal/mol'),