No output section in map_to_struct.wdl unit test

[stxue1]

The map_to_struct.wdl unit test has no output section:

wdl/SPEC.md

Lines 1422 to 1440 in 9c0b9cf

	workflow map_to_struct {
	String a = "beware"
	String b = "key"
	String c = "lookup"
	# What are the keys to this Struct?
	Words literal_syntax = Words {
	a: 10,
	b: 11,
	c: 12
	}
	# What are the keys to this Struct?
	Words map_coercion = {
	a: 10,
	b: 11,
	c: 12
	}
	}

For most runners, having no output section will result in no output. For example:

(venv3.12) heaucques@pop-os:~/Documents/wdl/wdl-tests/scripts/tests$ miniwdl run no_output.wdl
2024-06-17 14:37:58.328 wdl.w:wf workflow start :: name: "wf", source: "no_output.wdl", line: 3, column: 1, dir: "/home/heaucques/Documents/wdl/wdl-tests/scripts/tests/20240617_143758_wf"
2024-06-17 14:37:58.329 wdl.w:wf miniwdl :: version: "v1.12.0", uname: "Linux pop-os 6.8.0-76060800daily20240311-generic #202403110203~1715181801~22.04~aba43ee SMP PREEMPT_DYNAMIC Wed M x86_64"
2024-06-17 14:37:58.344 wdl.w:wf done
{
  "dir": "/home/heaucques/Documents/wdl/wdl-tests/scripts/tests/20240617_143758_wf",
  "outputs": {}
}

I'm unsure if the spec says execution engines should be able to output things when there is no output section in a workflow, but for consistency with the other unit tests, I think the struct declarations should be wrapped in an output section.