Workflow artifacts always sends version 1.0 artifact to sdc irrelevant of workflow version selected in operation. 

Steps: 
Create workflow 
Certify workflow 1.0 
Create new version of workflow 
Make changes in input/outputs of workflow 
DO NOT NAVIGATE TO COMPOSITION PAGE 
Certify workflow 2.0 
Create service/VF/PNF 
Add operation with workflow 
Select workflow 
Select workflow version 2.0 
Save operation 
Download TOSCA and artifact 
Validate bpmn artifact 

Expected : Artifact should contain data of workflow V 2.0 
Actual : Artifact contains data of workflow V 1.0