chore: bump the dependencies group in /Monarch.Tests with 1 update

Bumps the dependencies group in /Monarch.Tests with 1 update: [Mecha.xUnit](https://github.com/JaCraig/Mecha).


Updates `Mecha.xUnit` from 2.1.2 to 2.1.3
- [Changelog](https://github.com/JaCraig/Mecha/blob/main/CHANGELOG.md)
- [Commits](JaCraig/Mecha@v2.1.2...v2.1.3)

---
updated-dependencies:
- dependency-name: Mecha.xUnit
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: dependencies
...

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

Monarch.Tests/Monarch.Tests.csproj

@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <PackageReference Include="FluentAssertions" Version="6.12.0" />
-    <PackageReference Include="Mecha.xUnit" Version="2.1.2" />
+    <PackageReference Include="Mecha.xUnit" Version="2.1.3" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
     <PackageReference Include="xunit" Version="2.6.5" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.5.6">