flights: Set competition_id to None if unknown
flights: Set competition_id to None if unknown

shadowoneau/skylines,Turbo87/skylines,Turbo87/skylines,TobiasLohner/SkyLines,Harry-R/skylines,RBE-Avionik/skylines,dkm/skylines,snip/skylines,dkm/skylines,kerel-fs/skylines,skylines-project/skylines,skylines-project/skylines,snip/skylines,Harry-R/skylines,skylines-project/skylines,skylines-project/skylines,Turbo87/skylines,Harry-R/skylines,shadowoneau/skylines,TobiasLohner/SkyLines,shadowoneau/skylines,dkm/skylines,RBE-Avionik/skylines,Turbo87/skylines,RBE-Avionik/skylines,shadowoneau/skylines,kerel-fs/skylines,RBE-Avionik/skylines,Harry-R/skylines,snip/skylines,TobiasLohner/SkyLines,kerel-fs/skylines,dkm/skylines