請依照以下步驟：
sudo apt update
sudo apt install wget build-essential checkinstall
sudo apt install libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev libffi-dev zlib1g-dev
mkdir ~/tmp
cd ~/tmp
sudo wget https://www.python.org/ftp/python/3.9.2/Python-3.9.2.tgz
tar xzf Python-3.9.2.tgz
cd Python-3.9.2
sudo ./configure --enable-optimizations
sudo make altinstall
安裝完後，使用python3.9指令即可呼叫Python3.9.2
確認版本：
python3.9 -V
# Python 3.9.2
原本的Python3還是可以使用：
python3 -V
# Python 3.8.5