Update dependency FluentAssertions to v8

Author: renovate[bot]

tests/TBC.OpenAPI.SDK.ExchangeRates.Tests/TBC.OpenAPI.SDK.ExchangeRates.Tests.csproj

@@ -12,7 +12,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="FluentAssertions" Version="6.6.0" />
+    <PackageReference Include="FluentAssertions" Version="8.4.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />
     <PackageReference Include="Moq" Version="4.17.2" />
     <PackageReference Include="Moq.AutoMock" Version="3.3.0" />