Newer version of kani expects the presence of rustup #1
Description
First of all, thanks for this flake wrapper!
I used it successfully in my rust dev shell flake.nix. When trying to update the flake locally to the latest and greatest kani version, I noticed that the naked kani command succeeded but not cargo kani, which ended with a weird error "no such subcommand +nightly blah". It seems that now knai session expects the presence of rustup.
The corresponding kani PR is kani#2297 right after the 0.31.0 release I believe. Notice the new function toolchain_shorthand().
My question is if there is a way to mitigate it downstream here? If not, feel free to close the ticket.