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] <support@github.com>

Author: dependabot[bot]

Directory.Packages.props

@@ -6,7 +6,7 @@
   <ItemGroup>
     <!-- Static code analysis -->
     <PackageVersion Include="AspNetCore.HealthChecks.SqlServer" Version="9.0.0" />
-    <PackageVersion Include="FluentAssertions" Version="6.12.0" />
+    <PackageVersion Include="FluentAssertions" Version="8.8.0" />
     <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="9.0.10" />
     <PackageVersion Include="Microsoft.EntityFrameworkCore.SqlServer" Version="9.0.10" />
     <PackageVersion Include="SonarAnalyzer.CSharp" Version="10.15.0.120848" />