Consider dropping legacy frameworks

[SimonCropp]

eg net35 has been out for 19 years.

my preference would be to have the min supported moved to 472. out for 8 years

[SimonCropp]

@mikeebowen @micheloliveira-com @mkaszewiak can we get a ruling on this?

[mikeebowen]

Hi @SimonCropp , we will meet this week to discuss this and should have a ruling soon. Also, thanks for all your recent contributions to the SDK!

[SimonCropp]

@mikeebowen thanks. a bit more context, given the heavy string usage nature of this project, i would really like to see it leverage system.memory. where the min net classic is net462

https://www.nuget.org/packages/system.memory/#supportedframeworks-body-tab

[SimonCropp]

another nail is that it is not possible to run tests against those old frameworks with the modern test tools

see the current code...

    <When Condition=" '$(ProjectLoadStyle)' == 'net40' ">
      <PropertyGroup>
        <!-- We have some internal types that conflict -->
        <NoWarn>$(NoWarn);CS1685</NoWarn>
        <ProductTargetFrameworks>net40</ProductTargetFrameworks>
        <FrameworkTargetFrameworks>net40</FrameworkTargetFrameworks>
        <TestTargetFrameworks>net472</TestTargetFrameworks>
        <AssetsTargetFrameworks>net472</AssetsTargetFrameworks>
        <LatestTargetFramework>net472</LatestTargetFramework>
        <SamplesFrameworks>net472</SamplesFrameworks>
      </PropertyGroup>
    </When>

[SimonCropp]

also to consider: the current warnings. eg

warning : System.IO.Hashing 10.0.5 doesn't support net6.0 and has not been tested with it. Consider upgrading your TargetFramework to net8.0 or later. 

[SimonCropp]

@mikeebowen any updates?