Fix crash in series plugin when season_packs was specified in dict form without all options
Fix crash in series plugin when season_packs was specified in dict form without all options

tobinjt/Flexget,Flexget/Flexget,LynxyssCZ/Flexget,tobinjt/Flexget,ianstalk/Flexget,qk4l/Flexget,JorisDeRieck/Flexget,malkavi/Flexget,gazpachoking/Flexget,Danfocus/Flexget,malkavi/Flexget,jawilson/Flexget,Danfocus/Flexget,LynxyssCZ/Flexget,jawilson/Flexget,JorisDeRieck/Flexget,Flexget/Flexget,poulpito/Flexget,tobinjt/Flexget,JorisDeRieck/Flexget,gazpachoking/Flexget,crawln45/Flexget,OmgOhnoes/Flexget,ianstalk/Flexget,qk4l/Flexget,tobinjt/Flexget,jawilson/Flexget,qk4l/Flexget,OmgOhnoes/Flexget,malkavi/Flexget,OmgOhnoes/Flexget,crawln45/Flexget,Flexget/Flexget,Danfocus/Flexget,malkavi/Flexget,LynxyssCZ/Flexget,crawln45/Flexget,Flexget/Flexget,JorisDeRieck/Flexget,crawln45/Flexget,Danfocus/Flexget,poulpito/Flexget,poulpito/Flexget,ianstalk/Flexget,LynxyssCZ/Flexget,jawilson/Flexget