docs(readme): update python version

README.md

@@ -24,7 +24,7 @@ MegEngine is a fast, scalable, and user friendly deep learning framework with 3
 
 ## Installation
 
-**NOTE:** MegEngine now supports Python installation on Linux-64bit/Windows-64bit/MacOS(CPU-Only)-10.14+/Android 7+(CPU-Only) platforms with Python from 3.5 to 3.8. On Windows 10 you can either install the Linux distribution through [Windows Subsystem for Linux (WSL)](https://docs.microsoft.com/en-us/windows/wsl) or install the Windows distribution directly. Many other platforms are supported for inference.
+**NOTE:** MegEngine now supports Python installation on Linux-64bit/Windows-64bit/MacOS(CPU-Only)-10.14+/Android 7+(CPU-Only) platforms with Python from 3.6 to 3.9. On Windows 10 you can either install the Linux distribution through [Windows Subsystem for Linux (WSL)](https://docs.microsoft.com/en-us/windows/wsl) or install the Windows distribution directly. Many other platforms are supported for inference.
 
 ### Binaries
 

README_CN.md

@@ -34,7 +34,7 @@ MegEngine 是一个快速、可拓展、易于使用的深度学习框架，拥
 
 ## 安装说明
 
-**注意:** MegEngine 现在支持在 Linux-64bit/Windows-64bit/macos-10.14/Android 7+ 及其以上 (MacOS/Android只支持cpu) 等平台上安装 Python 包，支持Python3.5 到 Python3.8。对于 Windows 10 用户，可以通过安装 [Windows Subsystem for Linux (WSL)](https://docs.microsoft.com/en-us/windows/wsl) 进行体验，同时我们也原生支持Windows。MegEngine 也支持在很多其它平台上进行推理运算。
+**注意:** MegEngine 现在支持在 Linux-64bit/Windows-64bit/macos-10.14/Android 7+ 及其以上 (MacOS/Android只支持cpu) 等平台上安装 Python 包，支持Python3.6 到 Python3.9。对于 Windows 10 用户，可以通过安装 [Windows Subsystem for Linux (WSL)](https://docs.microsoft.com/en-us/windows/wsl) 进行体验，同时我们也原生支持Windows。MegEngine 也支持在很多其它平台上进行推理运算。
 
 ### 通过包管理器安装