cat /etc/centos-release
CentOS Linux release 7.6.1810 (Core)

yum install -y https://centos7.iuscommunity.org/ius-release.rpm

/etc/yum.repos.d 下に ius.repo などのリポジトリが追加されます。

yum search python36

yum install -y python36u python36u-libs python36u-devel python36u-pip

python3.6 --version
Python 3.6.7


 which python3.6
/usr/bin/python3.6

pip3.6 --version
pip 9.0.1 from /usr/lib/python3.6/site-packages (python 3.6)

sudo pip3.6 install requests

+.pyファイルの一番上に python3.6 明確に指定

#!/usr/bin/python3.6