fix escaping

{{cookiecutter.packer_name}}/packer.json

@@ -27,7 +27,6 @@
     {% endraw -%}
       "ssh_username"  : "ubuntu",
       "instance_type" : "m3.medium",
-    {% endraw -%}
       "source_ami_filter": {
         "filters": {
           "virtualization-type": "hvm",