add CI test artifacts to gitignore (#1916)

Author: jyoung8607

.gitignore

@@ -24,4 +24,7 @@ opendbc/can/packer_pyx.cpp
 opendbc/can/parser_pyx.cpp
 opendbc/can/packer_pyx.html
 opendbc/can/parser_pyx.html
-opendbc/dbc/*_generated.dbc
+opendbc/dbc/*_generated.dbc
+
+cppcheck-addon-ctu-file-list
+opendbc/safety/tests/coverage-out