dotnet script doesn't obey version

[phatcher]

I'm trying to run a script as NET Core 3.1 but dotnet script main.csx is not obeying the version, at the top of my file I have

#! "netcoreapp3.1"

and in lauch.json I have

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": ".NET Script Debug",
            "type": "coreclr",
            "request": "launch",
            "program": "dotnet",
            "args": [
                "exec",
                "${env:USERPROFILE}/.dotnet/tools/.store/dotnet-script/1.1.0/dotnet-script/1.1.0/tools/netcoreapp3.1/any/dotnet-script.dll",
                "${file}"
            ],
            "cwd": "${workspaceRoot}",
            "stopAtEntry": true
        }
    ]
}

My ```dotnet script --info`` reports

Version             : 1.1.0
Install location    : C:\Users\paulh\.dotnet\tools\.store\dotnet-script\1.1.0\dotnet-script\1.1.0\tools\net5.0\any
Target framework    : net5.0
.NET Core version   : 5.0.6
Platform identifier : win
Runtime identifier  : win10-x64

The script is old and can't run as .NET 5.0 as most of the referenced nuget packages do not support it. There are netcoreapp2.1 and netcoreapp3.1 directories as well as the net5.0 in the dotnet-script folder which suggests this si supported?

[seesharper]

The #! "netcoreapp3.1" won't work here. It was an early attempt to communicate to Omnisharp that we wanted compilation dependencies for a given target framework. It has never been used to resolve runtime dependencies for dotnet-script.