Test against 5.5.9
Test against 5.5.9

Since 5.5.9 is the lowest requirement we should also test against it.
nlemoine/papi,isotopsweden/wp-papi,isotopsweden/wp-papi,isotopsweden/wp-papi,nlemoine/papi,wp-papi/papi,wp-papi/papi,wp-papi/papi,nlemoine/papi