bump .NET SDK version

[dsyme]

Bump so we can use F# 5.0 features (.NET 5.0 SDK is now requried)

Looks like we also requires a .NET 3.1 SDK to actually run tests

[codecov]

Codecov Report

Merging #250 (dda64df) into dev (efa5640) will increase coverage by 0.39%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##              dev     #250      +/-   ##
==========================================
+ Coverage   63.62%   64.02%   +0.39%     
==========================================
  Files          19       19              
  Lines        5608     6136     +528     
  Branches     1416     1471      +55     
==========================================
+ Hits         3568     3928     +360     
- Misses       1269     1405     +136     
- Partials      771      803      +32     

Impacted Files	Coverage Δ
src/DiffSharp.Core/Tensor.fs	60.40% <0.00%> (-8.95%)	⬇️
src/DiffSharp.Core/DiffSharp.Numerical.fs	77.63% <0.00%> (-3.95%)	⬇️
src/DiffSharp.Core/Scalar.fs	8.33% <0.00%> (-0.49%)	⬇️
src/DiffSharp.Core/RawTensor.fs	85.62% <0.00%> (-0.38%)	⬇️
src/DiffSharp.Backends.Torch/Torch.RawTensor.fs	78.41% <0.00%> (+0.18%)	⬆️
src/DiffSharp.Core/Util.fs	55.56% <0.00%> (+0.24%)	⬆️
src/DiffSharp.Core/Data.fs	74.67% <0.00%> (+0.69%)	⬆️
src/DiffSharp.Core/Optim.fs	83.65% <0.00%> (+0.83%)	⬆️
src/DiffSharp.Core/Extensions.fs	54.29% <0.00%> (+1.81%)	⬆️
...iffSharp.Backends.Reference/Reference.RawTensor.fs	60.58% <0.00%> (+2.03%)	⬆️
... and 8 more

[gbaydin]

Hi @dsyme do you know why we need dotnet 3.1 for the tests?

[dsyme]

Hi @dsyme do you know why we need dotnet 3.1 for the tests?

The tests run as netcoreapp3.1, I think the CI installation technique doesn't automatically install the runtime for netcoreapp3.1.

I tried net5 when I did this but hit some issue - it might have BenchmarkDotnet, I'm not sure.

We should be able to move to purely net5 soon I think. Likely best to wait a month or two while other tools adjust

[gbaydin]

Ok, I could also test this within a Docker environment to inspect what's going on.