dotnet-sdk-3.1 fails docker build

[electricgull]

dotnet-sdk-3.1 fails docker build. Dotnet needs to be updated to dotnet-sdk-6.0 and use the new install scripts per:

https://learn.microsoft.com/en-us/dotnet/core/install/linux-ubuntu#2004 https://learn.microsoft.com/en-us/dotnet/core/install/linux-scripted-manual#scripted-install

https://github.com/microsoft/codeql-container/blob/46326644f2e39f7d2512a338b98b7e8d8a726435/Dockerfile#L50

[sargemonkey]

Agree, need to apply the fix