Update Thai program translation

Closes: #594011

debian/changelog

@@ -21,6 +21,7 @@ dpkg (1.15.8.5) UNRELEASED; urgency=low
   * Swedish (Peter Krefting).
   * French (Christian Perrier).
   * Simplified Chinese (Aron Xu). Closes: #594513
+  * Thai (Theppitak Karoonboonyanan). Closes: #594011
 
   [ Updated man page translations ]
   * German (Helge Kreutzmann).