tmunderground.json: Change expected content-type
tmunderground.json: Change expected content-type

hadess/libquvi-scripts-iplayer,alech/libquvi-scripts,DangerCove/libquvi-scripts,alech/libquvi-scripts,hadess/libquvi-scripts-iplayer,legatvs/libquvi-scripts,DangerCove/libquvi-scripts,legatvs/libquvi-scripts