fix: add_references for wfr to_dict

[masfaraud]

• What kind of changes does this PR introduce?

• [x] Bug fix: correcting bug by using same function for creating _references in to_dict of workflowstate

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

• [ ] Yes:

• [x] No

• Other information: