the angular template for .net 3.1 has not been updated. the version of angular is based on package.json file in the template
the easiest way to update a new project:
go the project root
delete ClientApp folder
create new angular project: ng new clientapp
rename folder clientapp to ClientApp
.note: as .net 3.1 support ends 12/13/2022, you really should not start new project with it. .net 6 changes how spa projects are developed and tested (uses node proxy rather than .net proxy), so you are better off starting .net 6