FirebaseDatabase dependency ~> 5 in version 0.3.8

[RachelPolachova]

Hey guys, I'm not able to update Firebase pod to version 6.13.0.

I'm getting this error:

[!] CocoaPods could not find compatible versions for pod "FirebaseDatabase":
  In Podfile:
    FirebaseDatabase (~> 6.1)

    RxFirebase/Database (= 0.3.8) was resolved to 0.3.8, which depends on
      RxFirebaseDatabase (~> 0.3) was resolved to 0.3.6, which depends on
        FirebaseDatabase (~> 5)

I tried to add RxFirebase/Database to my Podfile with '0.3.8' specification and without as well
pod 'RxFirebase/Database', '0.3.8'

According to this issue #28 it's already fixed, so I'm lost.

Could you help me please?