The REST API returns JSON payload with Content-Type "text/string"

[mgZenMaster]

This makes some clients need to bend over backwards to process the results. The fix for this seems to be fairly easy, just change the HUG annotations, for example:
@hug.post("/dep", output=hug.output_format.json)
This would be, of course, a change in the spacy-services repository, but I can't open an issue there.