Missing ssh private key file

[Snillocydoc]

Seeing the following output when building a virtualbox box:

$ packer build --only=virtualbox-iso.virtualbox -var version=22.05 -var-file nixos.auto.pkvars.hcl nixos.pkr.hcl
Error: 1 error(s) occurred:

* ssh_private_key_file is invalid: stat ./scripts/install_rsa: no such file or directory

  on nixos.pkr.hcl line 93:
  (source code not available)



==> Wait completed after 8 microseconds

==> Builds finished but no artifacts were created.

[zimbatm]

/cc @nickryand who converted the build to HCL