chore(deps): Bump xunit from 2.5.0 to 2.6.0 in /src

Bumps [xunit](https://github.com/xunit/xunit) from 2.5.0 to 2.6.0.
- [Commits](xunit/xunit@2.5.0...2.6.0)

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

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

src/SpaceTrackSdk.Tests/SpaceTrackSdk.Tests.csproj

@@ -19,7 +19,7 @@
         <PackageReference Include="JetBrains.Annotations" Version="2023.2.0" />
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.6.3" />
         <PackageReference Include="Shouldly" Version="4.2.1" />
-        <PackageReference Include="xunit" Version="2.5.0" />
+        <PackageReference Include="xunit" Version="2.6.0" />
         <PackageReference Include="xunit.runner.visualstudio" Version="2.5.0">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
             <PrivateAssets>all</PrivateAssets>