Increase size of release selection dialog

With the previous setttings, the line containing "sid" will be hidden
behind a "scrollbar".

Author: zeha

grml-debootstrap

@@ -892,7 +892,7 @@ prompt_for_release()
   local default_value="$RELEASE"
   RELEASE="$(dialog --stdout --title "${PN}" --default-item "$default_value" --menu \
             "Please enter the Debian release you would like to use for installation:" \
-            0 50 0 \
+            16 50 5 \
             bookworm Debian/12 \
             trixie   Debian/13 \
             sid      Debian/unstable)" \