Nim hash not updated in nimble.nix
**Describe the bug**
There's a comment in the file nix/nimble.nix :
>  WARNING: Requires manual updates when Nim compiler version changes.

It looks like it wasn't updated, resulting in a hash mismatch

> error: hash mismatch in fixed-output derivation '/nix/store/fzkjrmna2fxl540g3mxgc8jqf1v41d8v-source.drv':
         specified: sha256-sa0irAZjQRZLduEMBPf7sHlY1FigBJTR/vIH4ihii/w=
            got:    sha256-MVHf19UbOWk8Zba2scj06PxdYYOJA6OXrVyDQ9Ku6Us=
error: 1 dependencies of derivation '/nix/store/gd7dgkqnmp2kkkf1wpqjdj598bqna2ha-nimbus-eth2-24.12.0-4e440277.drv' failed to build


**To Reproduce**
1. Run a nix build using the nimbus-eth2 flake as an input
2. Get a hash mismatch

**Additional context**
@jakubgs since you commented in the `ethereum.nix` repo. The flake is great and makes everything super easy! I don't know what to suggest here though, obviously it is trivial to fix the hash but it's going to be missed again unless there's a CI test to catch it.