dotnet target specific framework
// global.json file in root of your project (as far as I understand,
// where you execute the 'dotnet' command, the CLI is going to go upwards
// until it finds this file and respect its contents - this means that it
// should not affect any other projects - even though its name is global.json)
{
"sdk": {
"version": "3.0.0"
}
}