Build Sonarr on Net6

Co-Authored-By: ta264 <ta264@users.noreply.github.com>

src/NzbDrone.Core.Test/MediaFiles/EpisodeImport/ImportApprovedEpisodesFixture.cs

@@ -302,7 +302,7 @@ namespace NzbDrone.Core.Test.MediaFiles.EpisodeImport
         [Test]
         public void should_get_relative_path_when_there_is_no_grandparent_mono()
         {
-            MonoOnly();
+            PosixOnly();
 
             var name = "Series.Title.S01E01.720p.HDTV.x264-Sonarr";
             var outputPath = "/";

src/NzbDrone.Core.Test/MediaFiles/EpisodeImport/Specifications/NotUnpackingSpecificationFixture.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using FizzWare.NBuilder;
 using FluentAssertions;
 using Moq;
@@ -74,7 +74,7 @@ namespace NzbDrone.Core.Test.MediaFiles.EpisodeImport.Specifications
         [Test]
         public void should_return_false_if_unopacking_on_linux()
         {
-            MonoOnly();
+            PosixOnly();
 
             GivenInWorkingFolder();
             GivenLastWriteTimeUtc(DateTime.UtcNow.AddDays(-5));