Fix Terraform examples for newer Nix versions

The examples do work for the Nix version that the book is tested
against, but this updates them to also work for newer Nix versions.

For more details, see:

Gabriella439/terraform-nixos-ng#9

Author: Gabriella439

manuscript/Terraform.md

@@ -445,7 +445,7 @@ module "ami" {
 }
 
 module "nixos" {
-  source = "github.com/Gabriella439/terraform-nixos-ng//nixos?ref=d8563d06cc65bc699ffbf1ab8d692b1343ecd927"
+  source = "github.com/Gabriella439/terraform-nixos-ng//nixos?ref=af1a0af57287851f957be2b524fcdc008a21d9ae"
   host = "root@${aws_instance.todo.public_ip}"
   flake = ".#default"
   arguments = [ "--build-host", "root@${aws_instance.todo.public_ip}" ]
@@ -467,7 +467,7 @@ let
       source = fetchFromGitHub {
         owner = "Gabriella439";
         repo = "terraform-nixos-ng";
-        rev = "d8563d06cc65bc699ffbf1ab8d692b1343ecd927";
+        rev = "af1a0af57287851f957be2b524fcdc008a21d9ae";
         hash = …;
       };
 
@@ -503,7 +503,7 @@ The first child module selects the correct NixOS AMI to use:
 
 ```hcl
 module "ami" {
-  source = "github.com/Gabriella439/terraform-nixos-ng//ami?ref=d8563d06cc65bc699ffbf1ab8d692b1343ecd927"
+  source = "github.com/Gabriella439/terraform-nixos-ng//ami?ref=af1a0af57287851f957be2b524fcdc008a21d9ae"
   release = "23.05"
   region = var.region
   system = "x86_64-linux"
@@ -514,7 +514,7 @@ module "ami" {
 
 ```hcl
 module "nixos" {
-  source = "github.com/Gabriella439/terraform-nixos-ng//nixos?ref=d8563d06cc65bc699ffbf1ab8d692b1343ecd927"
+  source = "github.com/Gabriella439/terraform-nixos-ng//nixos?ref=af1a0af57287851f957be2b524fcdc008a21d9ae"
 
   host = "root@${aws_instance.todo.public_ip}"
 

templates/continuous-deployment/main.tf

@@ -72,7 +72,7 @@ resource "aws_key_pair" "nixos-in-production" {
 }
 
 module "ami" {
-  source = "github.com/Gabriella439/terraform-nixos-ng//ami?ref=06d207ebc1c3de68d1bc52129d0fa23d61de5525"
+  source = "github.com/Gabriella439/terraform-nixos-ng//ami?ref=af1a0af57287851f957be2b524fcdc008a21d9ae"
   release = "23.05"
   region = var.region
   system = "x86_64-linux"
@@ -117,7 +117,7 @@ resource "null_resource" "wait" {
 }
 
 module "nixos" {
-  source = "github.com/Gabriella439/terraform-nixos-ng//nixos?ref=06d207ebc1c3de68d1bc52129d0fa23d61de5525"
+  source = "github.com/Gabriella439/terraform-nixos-ng//nixos?ref=af1a0af57287851f957be2b524fcdc008a21d9ae"
   host = "root@${aws_instance.todo.public_ip}"
   flake = ".#default"
   arguments = [ "--build-host", "root@${aws_instance.todo.public_ip}" ]

templates/terraform/main.tf

@@ -72,7 +72,7 @@ resource "aws_key_pair" "nixos-in-production" {
 }
 
 module "ami" {
-  source = "github.com/Gabriella439/terraform-nixos-ng//ami?ref=06d207ebc1c3de68d1bc52129d0fa23d61de5525"
+  source = "github.com/Gabriella439/terraform-nixos-ng//ami?ref=af1a0af57287851f957be2b524fcdc008a21d9ae"
   release = "23.05"
   region = var.region
   system = "x86_64-linux"
@@ -117,7 +117,7 @@ resource "null_resource" "wait" {
 }
 
 module "nixos" {
-  source = "github.com/Gabriella439/terraform-nixos-ng//nixos?ref=06d207ebc1c3de68d1bc52129d0fa23d61de5525"
+  source = "github.com/Gabriella439/terraform-nixos-ng//nixos?ref=af1a0af57287851f957be2b524fcdc008a21d9ae"
   host = "root@${aws_instance.todo.public_ip}"
   flake = ".#default"
   arguments = [ "--build-host", "root@${aws_instance.todo.public_ip}" ]