mus65

Add .NET 9 target

6

I had to disable a SonarSource analyzer and made use of the new `Lock` type, see separate Commits. CI is expected to fail because of missing .NET 9 binaries in...

Could you please make a new release of FluentFTP.Logging when you get a chance? I understand that #1152 alone is not worth doing a release, but it has been almost...