strict build of docs

[dsyme]

[dsyme]

Strict doc build is failing, because

1. Project cracking needs needs updating to .NET 7
2. fsdocs needs needs updating to .NET 7

cracking projects...
  skipping project 'FSharp.Compiler.Service.fsproj' because an error occurred while cracking it: System.Exception: error - SDK Resolver Failure: "The SDK resolver "Microsoft.DotNet.MSBuildWorkloadSdkResolver" failed while attempting to resolve the SDK "Microsoft.NET.Sdk". Exception: "System.IO.FileNotFoundException: Could not load file or assembly 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
File name: 'System.Runtime, Version=7.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
   at Microsoft.NET.Sdk.WorkloadMSBuildSdkResolver.WorkloadSdkResolver.Resolve(SdkReference sdkReference, SdkResolverContext resolverContext, SdkResultFactory factory)
   at Microsoft.Build.BackEnd.SdkResolution.SdkResolverService.ResolveSdk(Int32 submissionId, SdkReference sdk, LoggingContext loggingContext, ElementLocation sdkReferenceLocation, String solutionPath, String projectPath, Boolean interactive, Boolean isRunningInVisualStudio)""  D:\a\fsharp-compiler-docs\fsharp-compiler-docs\FSharp.Compiler.Service\FSharp.Compiler.Service.fsproj
log - 
   at Microsoft.FSharp.Core.PrintfModule.PrintFormatToStringThenFail@143[9](https://github.com/fsharp/fsharp-compiler-docs/runs/8093770493?check_suite_focus=true#step:9:10).Invoke(String message)
   at [email protected](String p) in /home/runner/work/FSharp.Formatting/FSharp.Formatting/src/fsdocs-tool/ProjectCracker.fs:line 454
Project cracking failed and --strict is on, exiting

[baronfel]

There's a new version of proj-info with some fixes for 6.0.400 and onwards cracking that you'll probably need to take to unblock this, then.

[dsyme]

@baronfel Updated some packages here https://github.com/fsprojects/FSharp.Formatting/pull/768