Update dependency FluentAssertions to 8.5.0

Author: renovate[bot]

Directory.Packages.props

@@ -11,7 +11,7 @@
 
     <PackageVersion Include="NSubstitute" Version="5.3.0" />
     <PackageVersion Include="NSubstitute.Analyzers.CSharp" Version="1.0.17" />
-    <PackageVersion Include="FluentAssertions" Version="8.4.0" />
+    <PackageVersion Include="FluentAssertions" Version="8.5.0" />
     <PackageVersion Include="FluentAssertions.Analyzers" Version="0.34.1" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
     <PackageVersion Include="xunit" Version="2.9.3" />