serialize to array of array instead of array

[yoanncouillec]

cwl-ts/src/models/d2sb/SBDraft2WorkflowModel.ts

Line 165 in c8355c5

base.inputs = <SBGWorkflowInputParameter[]> this.inputs.map(i => i.serialize());

Hi!
I faced a little bug while serializing CWL workflow.
When inputs type array contains more than one type it is serialize to an array of array like:
[ [ "int", "File" ] ]
However when the model contains only one typem the serialization is ok:
[ "File" ]