update pubmedcentral to match new schema override system
update pubmedcentral to match new schema override system

mehanig/scrapi,erinspace/scrapi,fabianvf/scrapi,CenterForOpenScience/scrapi,felliott/scrapi,felliott/scrapi,erinspace/scrapi,alexgarciac/scrapi,fabianvf/scrapi,mehanig/scrapi,CenterForOpenScience/scrapi,ostwald/scrapi,jeffreyliu3230/scrapi