poster: fix the search of poster source to a generic way
poster: fix the search of poster source to a generic way

flavioribeiro/clappr,wxmfront/clappr,tjenkinson/clappr,tarkanlar/clappr,shakin/clappr,leandromoreira/clappr,dayvson/clappr,wxmfront/clappr,MariadeAnton/clappr,Metrakit/clappr,kelonye/clappr,jfairley/clappr,leandromoreira/clappr,jfairley/clappr,clappr/clappr,MariadeAnton/clappr,wxmfront/clappr,shakin/clappr,Metrakit/clappr,Pyrotoxin/clappr,irongomme/clappr,tjenkinson/clappr,Peer5/clappr,irongomme/clappr,jfairley/clappr,dayvson/clappr,MariadeAnton/clappr,burakkp/clappr,shakin/clappr,clappr/clappr,leandromoreira/clappr,kelonye/clappr,Peer5/clappr,dayvson/clappr,flavioribeiro/clappr,Peer5/clappr,burakkp/clappr,burakkp/clappr,tarkanlar/clappr,Pyrotoxin/clappr,kelonye/clappr,flavioribeiro/clappr,tjenkinson/clappr,tarkanlar/clappr,Metrakit/clappr,Pyrotoxin/clappr,clappr/clappr,irongomme/clappr