`update.nix` suddenly failing to evaluate

Can't find `buildPlatform` for `drl` when generating the `shellHook`, even though `drl` evaluates fine outside of `update.nix`.

```
[…]
       error: evaluation aborted with the following error message: 'lib.customisation.callPackageWith: Function called without required argument "buildPlatform" at […]/nur-packages/pkgs/drl/common.nix:1'
```