Using terraform, ecr and docker image: Error in data "external" "hash": - Windows

On Windows 10 I'm trying to build this Project on GitHub: https://github.com/mathspace/terraform-aws-ecr-docker-image

It fails with this error:

Error: External Program Execution Failed
│
│   with data.external.hash,
│   on push.tf line 3, in data "external" "hash":
│    3:   program = [coalesce(var.hash_script, "C://VS//terraform-aws-ecr-docker-image//hash.sh"), var.source_path]
│
│ The data source received an unexpected error while attempting to execute the program.
│
│ Program: C://VS//terraform-aws-ecr-docker-image//hash.sh
│ Error: fork/exec C://VS//terraform-aws-ecr-docker-image//hash.sh: %1 is not a valid Win32 application.

I'm stumped as to what the problem is with the External Hash being generated?

It's a clone of this popular Git Repo so unless something changed in the last few years it doesn't work - despite 26 stars.

This is the code, hardcoding the Module's Path didn't make any difference:

# Calculate hash of the Docker image source contents
data "external" "hash" {
  program = [coalesce(var.hash_script, "${path.module}/hash.sh"), var.source_path]
}

# Build and push the Docker image whenever the hash changes
resource "null_resource" "push" {
  triggers = {
    hash = data.external.hash.result["hash"]
  }

  provisioner "local-exec" {
    command     = "${coalesce(var.push_script, "${path.module}/push.sh")} ${var.source_path} ${aws_ecr_repository.repo.repository_url} ${var.tag}"
    interpreter = ["bash", "-c"]
  }
}