update gitignore so I dont have to see celerybeat.db all the time
update gitignore so I dont have to see celerybeat.db all the time

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