Catch IOException as well in test

Author: acogoluegnes

src/test/java/com/rabbitmq/client/test/functional/SaslMechanisms.java

@@ -118,6 +118,8 @@ public void connectionCloseAuthFailure(String username, String password) throws
             if (paf instanceof AuthenticationFailureException) {
                 fail("Not expecting AuthenticationFailureException " + failDetail);
             }
+        } catch (IOException e) {
+          // can happen if the broker closes the connection abruptly
         }
     }