Test: Fix the Packer test template.

test_files/template.pkr.hcl

+# vi: ft=tf
+
 packer {
   required_plugins {
     amazon = {
-      version = ">= 0.0.2"
       source  = "github.com/hashicorp/amazon"
+      version = "~> 1"
     }
   }
 }