The plugin "https://github.com/josenk/terraform-provider-esxi" v1.7.1 is now official listed and supported by terraform 0.13 registry provider.

But to get it to work you either have to do some code modifications, especially on ESXi 6.5

1. Add to the top of ESXi/main.tf:

terraform {
  required_version = ">= 0.13"
}

2. Add new file to ESXi/versions.tf

terraform {
  required_version = ">= 0.13"
  required_providers {
    esxi = {
      source = "registry.terraform.io/josenk/esxi"
      #
      # For more information, see the provider source documentation:
      #
      # https://github.com/josenk/terraform-provider-esxi
      # https://registry.terraform.io/providers/josenk/esxi
      #
    }
  }
}

Then start working with terraform init && terraform apply and proceed with the other steps.