chore: update tests project to dotnet 8 (#363)

Author: Meir017

src/FluentAssertions.Analyzers.TestUtils/CsProjectArguments.cs

@@ -3,7 +3,7 @@
 
 public class CsProjectArguments
 {
-    public TargetFramework TargetFramework { get; set; } = TargetFramework.Net6_0;
+    public TargetFramework TargetFramework { get; set; } = TargetFramework.Net8_0;
     public string[] Sources { get; set; }
     public PackageReference[] PackageReferences { get; set; } = Array.Empty<PackageReference>();
     public string Language { get; set; } = LanguageNames.CSharp;

src/FluentAssertions.Analyzers.TestUtils/CsProjectGenerator.cs

@@ -81,7 +81,7 @@ public static Project CreateProject(string[] sources, string language = Language
             {
                 Language = language,
                 Sources = sources,
-                TargetFramework = TargetFramework.Net6_0,
+                TargetFramework = TargetFramework.Net8_0,
             };
             return CreateProject(arguments).AddMetadataReferences(References);
         }

src/FluentAssertions.Analyzers.TestUtils/PackageReference.cs

@@ -26,9 +26,9 @@ private PackageReference(string name, string version, string path)
 
     internal static PackageReference NETStandard2_0 = new("NETStandard.Library", "2.0.3", "build/netstandard2.0/ref/");
     internal static PackageReference NETStandard2_1 = new("NETStandard.Library.Ref", "2.1.0", "ref/netstandard2.1/ref/");
-    internal static PackageReference DotNet6 = new("Microsoft.NETCore.App.Ref", "6.0.25", "ref/net6.0/");
-    internal static PackageReference DotNet7 = new("Microsoft.NETCore.App.Ref", "7.0.14", "ref/net7.0/");
-    internal static PackageReference DotNet8 = new("Microsoft.NETCore.App.Ref", "8.0.0", "ref/net8.0/");
+    internal static PackageReference DotNet6 = new("Microsoft.NETCore.App.Ref", "6.0.31", "ref/net6.0/");
+    internal static PackageReference DotNet7 = new("Microsoft.NETCore.App.Ref", "7.0.20", "ref/net7.0/");
+    internal static PackageReference DotNet8 = new("Microsoft.NETCore.App.Ref", "8.0.6", "ref/net8.0/");
 
     internal static IEnumerable<PackageReference> AllDependencies => _allDependencies;
 }