PaddlePaddle.org static ip was changed, need to change the known hosts (#9547)

Author: cs2be

.travis.yml

@@ -34,7 +34,7 @@ addons:
       - automake
       - libtool
       - ccache
-  ssh_known_hosts: 52.76.173.135
+  ssh_known_hosts: 13.229.163.131
 before_install:
   - if [[ "$JOB" == "check_style" ]]; then sudo ln -s /usr/bin/clang-format-3.8 /usr/bin/clang-format; fi
   # Paddle is using protobuf 3.1 currently. Protobuf 3.2 breaks the compatibility. So we specify the python