Support Up-to-date dependencies

[davidchristian1]

Currently, this package depends on rxdart ^0.26.0. Can you please update the rxdart version (to rxdart ^0.27.3)? I want to use this package but I cannot install it because of this version issue :( Thank you.

[m-spiridon]

I would also appreciate this update. Thank you!

[mohanadshaban]

Yes Please +++

[JThorvid]

I would appreciate this as well, since this causes problems for me with the assets_audio_player.
There is even a fork that uses the newer rxdart (master...ariefwijaya:master). I have not tried it though.

[neckaros]

thanks for the info. I merged a pull request from the repo you provided @JThorvid