Update fedimint to 0.4.4 or 0.5.0.

[toyota-corolla0]

Hello, was hoping this could happen so I could start messing with new handle_rpc_command stuff. I tried to update my repo but I don't understand nix enough. Thanks!

[toyota-corolla0]

@justinmoon @m1sterc001guy
Would really appreciate if this was expedited. Thanks!

[m1sterc001guy]

I will try and get this updated to 0.5 soon. If you want to be unblocked sooner, I rebased the Roastr project on top of 0.5 and you can use that as an example.

https://github.com/m1sterc001guy/roastr