Bump FluentAssertions from 5.10.3 to 6.3.0 (#1680)

Bumps [FluentAssertions](https://github.com/fluentassertions/fluentassertions) from 5.10.3 to 6.3.0.
- [Release notes](https://github.com/fluentassertions/fluentassertions/releases)
- [Changelog](https://github.com/fluentassertions/fluentassertions/blob/master/AcceptApiChanges.ps1)
- [Commits](fluentassertions/fluentassertions@5.10.3...6.3.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

test/Directory.Build.props

@@ -15,7 +15,7 @@
     <ItemGroup>
         <PackageReference Include="xunit" Version="2.4.1"/>
         <PackageReference Include="AutoFixture" Version="4.17.0"/>
-        <PackageReference Include="FluentAssertions" Version="5.10.3"/>
+        <PackageReference Include="FluentAssertions" Version="6.3.0"/>
     </ItemGroup>
 
     <ItemGroup>