Fix nix flake

[kayagokalp]

as of #18 nix flake is broken, fails with:

error: builder for '/nix/store/bigjll2fjf9zn29fsrvhv90vqja5wxf4-rust-workspace-unknown.drv' failed with exit code 101;
       last 10 log lines:
       >                 ...
       >           ld: symbol(s) not found for architecture arm64
       >           clang-16: error: linker command failed with exit code 1 (use -v to see invocation)
       >           
       >
       >
       > error: aborting due to previous error
       >
       >
       > [naersk] cargo returned with exit code 101, exiting
       For full logs, run 'nix log /nix/store/bigjll2fjf9zn29fsrvhv90vqja5wxf4-rust-workspace-unknown.drv'.