Bump FluentAssertions from 7.0.0 to 8.0.0

Bumps [FluentAssertions](https://github.com/fluentassertions/fluentassertions) from 7.0.0 to 8.0.0.
- [Release notes](https://github.com/fluentassertions/fluentassertions/releases)
- [Changelog](https://github.com/fluentassertions/fluentassertions/blob/develop/AcceptApiChanges.ps1)
- [Commits](fluentassertions/fluentassertions@7.0.0...8.0.0)

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

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

tests/Serilog.Formatting.Log4Net.Tests.csproj

@@ -7,7 +7,7 @@
 
   <ItemGroup>
     <PackageReference Include="coverlet.collector" Version="6.0.3" PrivateAssets="all" />
-    <PackageReference Include="FluentAssertions" Version="7.0.0" />
+    <PackageReference Include="FluentAssertions" Version="8.0.0" />
     <PackageReference Include="GitHubActionsTestLogger" Version="2.4.1" PrivateAssets="all" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="PublicApiGenerator" Version="11.3.0" />