add new spider code in spider.py for crawling error message from website.

run bash start.sh in current directory to generate new externalErrorMsg_${date}.tar.gz file, for example externalErrorMsg_20210928.tar.gz.

upload above tar file into bos https://paddlepaddledeps.bj.bcebos.com paddlepaddledeps bucket, and copy download link ${download_url}. *Be careful not to delete original tar file*.

compute md5 value of above tar file ${md5}, and modify cmake/third_party.cmake file

set(URL  "${download_url}" CACHE STRING "" FORCE)
file_download_and_uncompress(${URL} "externalError" MD5 ${md5})

for example:

set(URL  "https://paddlepaddledeps.bj.bcebos.com/externalErrorMsg_20210928.tar.gz" CACHE STRING "" FORCE)
file_download_and_uncompress(${URL} "externalError" MD5 a712a49384e77ca216ad866712f7cafa)

commit your changes, and create pull request.