Bump xunit from 2.4.1 to 2.4.2 in /src

Bumps [xunit](https://github.com/xunit/xunit) from 2.4.1 to 2.4.2.
- [Release notes](https://github.com/xunit/xunit/releases)
- [Commits](xunit/xunit@2.4.1...2.4.2)

---
updated-dependencies:
- dependency-name: xunit
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

src/BBT.StructureTools.Tests/BBT.StructureTools.Tests.csproj

@@ -24,7 +24,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.2.0" />
     <PackageReference Include="Moq" Version="4.18.1" />
     <PackageReference Include="Ninject" Version="3.3.6" />
-    <PackageReference Include="xunit" Version="2.4.1" />
+    <PackageReference Include="xunit" Version="2.4.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>