Updated transfer_characteristics to color_transfer

Current implementation is looking for "transfer_characteristics" within ffprobe data as an attribute that has to match to determine if a file is HDR or not. However, current ffprobe is not showing this attribute on HDR files. I am proposing changing this attribute to "color_transfer" which does show up on HDR files.

FlowPlugins/CommunityFlowPlugins/video/checkHdr/1.0.0/index.js

@@ -38,7 +38,7 @@ var plugin = function (args) {
         for (var i = 0; i < args.inputFileObj.ffProbeData.streams.length; i += 1) {
             var stream = args.inputFileObj.ffProbeData.streams[i];
             if (stream.codec_type === 'video'
-                && stream.transfer_characteristics === 'smpte2084'
+                && stream.color_transfer === 'smpte2084'
                 && stream.color_primaries === 'bt2020'
                 && stream.color_range === 'tv') {
                 isHdr = true;