deps: Bump FluentAssertions from 6.12.0 to 8.8.0

---
updated-dependencies:
- dependency-name: FluentAssertions
  dependency-version: 8.8.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

tests/Conduit.Api.Tests/Conduit.Api.Tests.csproj

@@ -10,7 +10,7 @@
 
   <ItemGroup>
     <PackageReference Include="coverlet.collector" Version="6.0.0" />
-    <PackageReference Include="FluentAssertions" Version="6.12.0" />
+    <PackageReference Include="FluentAssertions" Version="8.8.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
     <PackageReference Include="Moq" Version="4.20.69" />
     <PackageReference Include="xunit" Version="2.4.2" />