add rpyc class and update Dockerfile

OpenshotService/openshot_video_generator.py

@@ -410,6 +410,6 @@ class video_service(rpyc.Service):
 
 
 from rpyc.utils.server import ThreadedServer
-t = ThreadedServer(video_service, port=18861)
+t = ThreadedServer(video_service, port=8888)
 t.start()
 print('service started')