package/libstrophe: bump to version 0.9.3

package/libstrophe: bump to version 0.9.3

Changes:

  * PLAIN mechanism is used only when no other mechanisms are supported
  * Legacy authentication is disabled by default, can be enabled with
    connection flag XMPP_CONN_FLAG_LEGACY_AUTH
  * Session is not established if it is optional
  * Fixed a bug causing a reused connection not to cleanup properly
  * Improved debug logging in OpenSSL module
  * Few memory leaks fixed

Signed-off-by: Michael Vetter <jubalh@iodoru.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>