Update to dotnet 7.

[nojaf]

I was able to generate the Fantomas API docs locally with this change.
//cc @dsyme

[nojaf]

At one point I did see this error on my local machine:

/home/runner/work/FSharp.Formatting/FSharp.Formatting/src/FSharp.Formatting.Common/YaafFSharpScripting.fs:line 144
   at FSharp.Formatting.CodeFormat.CodeFormatter.processSourceCode@345-1.Invoke(StringReader reader) in /home/runner/work/FSharp.Formatting/FSharp.Formatting/src/FSharp.Formatting.CodeFormat/CodeFormatAgent.fs:line 363
   at Microsoft.FSharp.Control.AsyncPrimitives.CallThenInvoke[T,TResult](AsyncActivation`1 ctxt, TResult result1, FSharpFunc`2 part2) in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 510
   at Microsoft.FSharp.Control.Trampoline.Execute(FSharpFunc`2 firstAction) in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 112
--- End of stack trace from previous location ---
   at Microsoft.FSharp.Control.AsyncResult`1.Commit() in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 454
   at Microsoft.FSharp.Control.AsyncPrimitives.QueueAsyncAndWaitForResultSynchronously[a](CancellationToken token, FSharpAsync`1 computation, FSharpOption`1 timeout) in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 1140
   at Microsoft.FSharp.Control.AsyncPrimitives.RunSynchronously[T](CancellationToken cancellationToken, FSharpAsync`1 computation, FSharpOption`1 timeout) in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 1167
   at Microsoft.FSharp.Control.FSharpAsync.RunSynchronously[T](FSharpAsync`1 computation, FSharpOption`1 timeout, FSharpOption`1 cancellationToken) in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 1511
   at FSharp.CodeFormat.Tests.getContentAndToolTip(String source) in /home/runner/work/FSharp.Formatting/FSharp.Formatting/tests/FSharp.CodeFormat.Tests/CodeFormatTests.fs:line 124
   at [email protected](String x)
   at FSharp.CodeFormat.Tests.Functions and methods are in spans of 'f' class() in /home/runner/work/FSharp.Formatting/FSharp.Formatting/tests/FSharp.CodeFormat.Tests/CodeFormatTests.fs:line 207
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Void** arguments, Signature sig, Boolean isConstructor)
   at System.Reflection.MethodInvoker.Invoke(Object obj, IntPtr* args, BindingFlags invokeAttr)
  Failed Functions and methods are in spans of 'f' class - custom CSS [3 ms]
  Error Message:
   System.IO.FileNotFoundException : Could not load file or assembly 'Microsoft.Build.Utilities.Core, Version=15.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.

it is trying to use the legacy resolver for some reason.
Then it went away, but I assume the problem is still there.
Do we need a change for fsChecker.GetProjectOptionsFromScript?

[nojaf]

I'm not going to claim I fully understand how this works but if you target net6.0 the MSBuild DLLs are not published to the output folder. Using net7.0 they are and the test pass.

The next bottleneck would be getting FAKE to work on net7. (See fsprojects/FAKE#2719)

[nojaf]

Hello @dsyme, would it be ok if we changed the FAKE script to a project instead?
See docs.
It would resolve the current net7 problem.

[dsyme]

@nojaf Thanks! this is great

Even better would be to remove the use of FAKE from this core project.