deps(test): update dependency fluentassertions to 8.8.0 (#973)

This PR contains the following updates:

| Package | Change | Age | Confidence |
|---|---|---|---|
|
[FluentAssertions](https://xceed.com/products/unit-testing/fluent-assertions/)
([source](https://redirect.github.com/fluentassertions/fluentassertions))
| `8.7.1` -> `8.8.0` |
[![age](https://developer.mend.io/api/mc/badges/age/nuget/FluentAssertions/8.8.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/nuget/FluentAssertions/8.7.1/8.8.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>fluentassertions/fluentassertions (FluentAssertions)</summary>

###
[`v8.8.0`](https://redirect.github.com/fluentassertions/fluentassertions/releases/tag/8.8.0)

[Compare
Source](https://redirect.github.com/fluentassertions/fluentassertions/compare/8.7.1...8.8.0)

<!-- Release notes generated using configuration in .github/release.yml
at main -->

#### What's Changed

##### New features

- Add support for MSTest4 by
[@&#8203;jnyrup](https://redirect.github.com/jnyrup) in
[#&#8203;3111](https://redirect.github.com/fluentassertions/fluentassertions/pull/3111)

##### Improvements

- Allow WithoutMessage when using Should().Throw() and ThrowAsync() by
[@&#8203;dennisdoomen](https://redirect.github.com/dennisdoomen) in
[#&#8203;3100](https://redirect.github.com/fluentassertions/fluentassertions/pull/3100)
- Improve reporting of the differences between long strings by
[@&#8203;dennisdoomen](https://redirect.github.com/dennisdoomen) in
[#&#8203;3101](https://redirect.github.com/fluentassertions/fluentassertions/pull/3101)
- Allow customizing the equivalency behavior for BeXmlSerializable by
[@&#8203;logiclrd](https://redirect.github.com/logiclrd) in
[#&#8203;3107](https://redirect.github.com/fluentassertions/fluentassertions/pull/3107)

##### Documentation

- Add docs for `config` parameter by
[@&#8203;jnyrup](https://redirect.github.com/jnyrup) in
[#&#8203;3104](https://redirect.github.com/fluentassertions/fluentassertions/pull/3104)

##### Others

- Refreshed readme by
[@&#8203;dennisdoomen](https://redirect.github.com/dennisdoomen) in
[#&#8203;3106](https://redirect.github.com/fluentassertions/fluentassertions/pull/3106)
- Merge hotfix 8.7.1 back to main by
[@&#8203;dennisdoomen](https://redirect.github.com/dennisdoomen) in
[#&#8203;3109](https://redirect.github.com/fluentassertions/fluentassertions/pull/3109)
- Fix release notes by
[@&#8203;jnyrup](https://redirect.github.com/jnyrup) in
[#&#8203;3112](https://redirect.github.com/fluentassertions/fluentassertions/pull/3112)
- Bump github/codeql-action from 3 to 4 by
[@&#8203;dependabot](https://redirect.github.com/dependabot)\[bot] in
[#&#8203;3113](https://redirect.github.com/fluentassertions/fluentassertions/pull/3113)

**Full Changelog**:
<fluentassertions/fluentassertions@8.7.1...8.8.0>

</details>

---

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test/Directory.Build.props

@@ -9,7 +9,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="FluentAssertions" Version="8.7.1" />
+        <PackageReference Include="FluentAssertions" Version="8.8.0" />
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
         <PackageReference Include="xunit" Version="2.9.3" />
         <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5">