Fixed wrong .meta file exception in .gitignore
Fixed wrong .meta file exception in .gitignore

MainThreadScheduler.cs.meta was accidentally added instead of the
intended MainThreadDispatcher.cs.meta.

cruwel/UniRx,InvertGames/UniRx,cruwel/UniRx,zillakot/UniRx,zhutaorun/UniRx,zhutaorun/UniRx,ppcuni/UniRx,ic-sys/UniRx,endo0407/UniRx,Useurmind/UniRx,neuecc/UniRx,juggernate/UniRx,zillakot/UniRx,m-ishikawa/UniRx,saruiwa/UniRx,OrangeCube/UniRx,juggernate/UniRx,ufcpp/UniRx,kimsama/UniRx,zillakot/UniRx,Useurmind/UniRx,OC-Leon/UniRx,Useurmind/UniRx,juggernate/UniRx,zhutaorun/UniRx,ic-sys/UniRx,ataihei/UniRx,ic-sys/UniRx,cruwel/UniRx,TORISOUP/UniRx