chore: bump Mecha.xUnit in /FileCurator.Tests in the dependencies group

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


Updates `Mecha.xUnit` from 3.1.1 to 3.1.2
- [Changelog](https://github.com/JaCraig/Mecha/blob/main/CHANGELOG.md)
- [Commits](JaCraig/Mecha@v3.1.1...v3.1.2)

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

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

Author: dependabot[bot]

FileCurator.Tests/FileCurator.Tests.csproj

@@ -109,7 +109,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Mecha.xUnit" Version="3.1.1" />
+    <PackageReference Include="Mecha.xUnit" Version="3.1.2" />
     <PackageReference Include="coverlet.collector" Version="6.0.4">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>