Add transient to subtitle stream export

lib/plexapi/media.py

@@ -369,6 +369,7 @@ class SubtitleStream(MediaPartStream):
         self.headerCompression = data.attrib.get('headerCompression')
         self.key = data.attrib.get('key')
         self.requiredBandwidths = data.attrib.get('requiredBandwidths')
+        self.transient = data.attrib.get('transient')
 
 
 @utils.registerPlexObject

plexpy/exporter.py

@@ -330,7 +330,8 @@ class Export(object):
                             'forced': None,
                             'format': None,
                             'headerCompression': None,
-                            'key': None
+                            'key': None,
+                            'transient': None
                         }
                     }
                 },
@@ -638,7 +639,8 @@ class Export(object):
                             'forced': None,
                             'format': None,
                             'headerCompression': None,
-                            'key': None
+                            'key': None,
+                            'transient': None
                         }
                     }
                 },