Avoid the following seen when running ec2_ami tests on python3,
presumably because the return type of `map` is different between
python2 and python3.
```
Traceback (most recent call last):
File "/tmp/ansible_e44v27uj/ansible_module_ec2_snapshot_facts.py", line 242, in <module>
main()
File "/tmp/ansible_e44v27uj/ansible_module_ec2_snapshot_facts.py", line 238, in main
list_ec2_snapshots(connection, module)
File "/tmp/ansible_e44v27uj/ansible_module_ec2_snapshot_facts.py", line 193, in list_ec2_snapshots
snapshots = connection.describe_snapshots(SnapshotIds=snapshot_ids, OwnerIds=owner_ids, RestorableByUserIds=restorable_by_user_ids, Filters=filters)
File "/usr/local/lib/python3.5/dist-packages/botocore/client.py", line 312, in _api_call
return self._make_api_call(operation_name, kwargs)
File "/usr/local/lib/python3.5/dist-packages/botocore/client.py", line 575, in _make_api_call
api_params, operation_model, context=request_context)
File "/usr/local/lib/python3.5/dist-packages/botocore/client.py", line 630, in _convert_to_request_dict
api_params, operation_model)
File "/usr/local/lib/python3.5/dist-packages/botocore/validate.py", line 291, in serialize_to_request
raise ParamValidationError(report=report.generate_report())
botocore.exceptions.ParamValidationError: Parameter validation failed:
Invalid type for parameter OwnerIds, value: <map object at 0x7ff577511048>, type: <class 'map'>, valid types: <class 'list'>, <class 'tuple'>
```
https://github.com/ansible/ansible/pull/30435#issuecomment-330750498
5900fee67a