libsoup: update to 2.60.3.

Changes in libsoup from 2.60.2 to 2.60.3:

* heap-buffer-overflow in soup_ntlm_parse_challenge()
  [#788037, Milan Crha]

* session: don't request Keep-Alive for upgraded connections
  [#788723, Lionel Landwerlin]

        * soup-headers: accept any 3 digit number as message status code
  [#792124, Carlos Garcia Campos]

(wiz)