chore(deps): update dependency fluentassertions to v8

Author: renovate[bot]

src/ReactiveMarbles.PropertyChanged.SourceGenerator.Tests/ReactiveMarbles.PropertyChanged.SourceGenerator.Tests.csproj

@@ -12,7 +12,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.11.0" allowedVersions="[3.11.0]" PrivateAssets="all" />
     <PackageReference Include="System.Reactive" Version="6.0.2" />
-    <PackageReference Include="FluentAssertions" Version="6.2.0" />
+    <PackageReference Include="FluentAssertions" Version="8.6.0" />
     <PackageReference Include="MSTest.TestFramework" Version="3.10.2" />
     <PackageReference Include="MSTest.TestAdapter" Version="3.10.2" />    
   </ItemGroup>