RxSwift 6.0 Support

[huoda1237]

[!] CocoaPods could not find compatible versions for pod "RxSwift":
In snapshot (Podfile.lock):
RxSwift (= 6.0.0-rc.2)

In Podfile:
RxCocoa (= 6.0.0-rc.2) was resolved to 6.0.0-rc.2, which depends on
RxSwift (= 6.0.0-rc.2)

RxDataSources (~> 4.0) was resolved to 4.0.1, which depends on
  RxSwift (~> 5.0)

[Shai Mishali]

I'm hoping to make a new release of RxDataSources once we release RxSwift 6 (soon).

[Shai Mishali]

Part of RxDataSources 5.0.0.