Update sovrnBidAdapter.js: support plcmt (#11704)

Author: patmmccann

modules/sovrnBidAdapter.js

@@ -28,6 +28,7 @@ const ORTB_VIDEO_PARAMS = {
   'h': (value) => isInteger(value),
   'startdelay': (value) => isInteger(value),
   'placement': (value) => isInteger(value) && value >= 1 && value <= 5,
+  'plcmt': (value) => isInteger(value) && value >= 1 && value <= 4,
   'linearity': (value) => [1, 2].indexOf(value) !== -1,
   'skip': (value) => [0, 1].indexOf(value) !== -1,
   'skipmin': (value) => isInteger(value),