step1：
yum -y install gcc
yum install zlib zlib-devel
step2： cd /usr/bin/ mv python python.bak
step3：下载python3.6.3，解压并进入目录执行执行 ./configure -prefix=/usr/local/python/python3 ； make ; makeinstall
step4：执行 ln -s /usr/local/python/python3/bin/python3 /usr/bin/python
ln -s /usr/local/python/python3/bin/pip3 /usr/bin/pip3