未找到框架“Microsoft.AspNetCore.App”，版本“3.1.0”

在 Mac 上，我安装了 Net Core：

.NET SDKs installed:
  5.0.100 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 5.0.0 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 5.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

我能够运行 Net Core 5.0 项目，但是当我尝试运行 NET Core 3.1 项目时，我得到：

It was not possible to find any compatible framework version
The framework 'Microsoft.AspNetCore.App', version '3.1.0' was not found.

我需要安装 SKD 3.1 吗？

回答