chore: add marshall benchmark (#14)

bench/marshall.py

@@ -0,0 +1,19 @@
+import timeit
+
+from dbus_fast import Message
+
+message = Message(
+    destination="org.bluez",
+    path="/",
+    interface="org.freedesktop.DBus.ObjectManager",
+    member="GetManagedObjects",
+)
+
+
+def marhsall_bluez_get_managed_objects_message():
+    message._marshall()
+
+
+count = 1000000
+time = timeit.Timer(marhsall_bluez_get_managed_objects_message).timeit(count)
+print(f"Marshalling {count} bluez get managed objects messages took {time} seconds")