Correct the database mirroring partner envchange handle code. (#110)

* based on this TDS doc page https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-tds/2b3eb7e5-d43d-4d1b-bf4d-76b9e3afc791

Author: andrei-mihaila

lib/tds/tokens.ex

@@ -355,9 +355,9 @@ defmodule Tds.Tokens do
 
         0x0D ->
           <<
-            0x00,
             new_value_size::unsigned-8,
             _new_value::binary(new_value_size, 16),
+            0x00,
             rest::binary
           >> = tail