pass vpc_subnet_id explicitly to avoid amazon.aws error (#199)

pass vpc_subnet_id explicitly to avoid amazon.aws error, fixes #46

The upstream code there can call  their get_default_vpc(), which will
fail if our users do not have one in their AWS account.

It is common practice to remove it and build a more restricted one -
causing errors for users that do so.

src/molecule_plugins/ec2/cookiecutter/{{cookiecutter.molecule_directory}}/{{cookiecutter.scenario_name}}/destroy.yml

@@ -89,6 +89,7 @@
             profile: "{{ item.aws_profile | default(omit) }}"
             region: "{{ item.region | default(omit) }}"
             instance_ids: "{{ instance_config | map(attribute='instance_ids') | flatten }}"
+            vpc_subnet_id: "{{ item.vpc_subnet_id }}"
             state: absent
           loop: "{{ platforms }}"
           loop_control: