Ubuntu 18.04 upgrade python3.6 to 3.7
apt-get update
apt-get install python3.7
update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.6 1
update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.7 2
update-alternatives --config python3
选择python3.7