Update CODEOWNERS

In convo with Eb adding myself to 12 and 20 to ccsn

Author: aurimontem

CODEOWNERS

@@ -128,8 +128,8 @@ star/test_suite/wd_he_shell_ignition @wmwolf
 star/test_suite/wd_nova_burst @wmwolf
 star/test_suite/wd_stable_h_burn @wmwolf
 
-star/test_suite/12M_pre_ms_to_core_collapse @Debraheem
-star/test_suite/20M_pre_ms_to_core_collapse @Debraheem
+star/test_suite/12M_pre_ms_to_core_collapse @Debraheem @aurimontem
+star/test_suite/20M_pre_ms_to_core_collapse @Debraheem @aurimontem
 star/test_suite/split_burn_big_net
 star/test_suite/zams_to_cc_80 @Debraheem
 star/test_suite/20M_z2m2_high_rotation