deps(test): update dependency xunit.runner.visualstudio to 3.1.5 (#957)

Coming soon: The Renovate bot (GitHub App) will be renamed to Mend. PRs
from Renovate will soon appear from 'Mend'. Learn more
[here](https://redirect.github.com/renovatebot/renovate/discussions/37842).

This PR contains the following updates:

| Package | Change | Age | Confidence |
|---|---|---|---|
|
[xunit.runner.visualstudio](https://redirect.github.com/xunit/visualstudio.xunit)
| `3.1.4` -> `3.1.5` |
[![age](https://developer.mend.io/api/mc/badges/age/nuget/xunit.runner.visualstudio/3.1.5?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/nuget/xunit.runner.visualstudio/3.1.4/3.1.5?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Configuration

📅 **Schedule**: Branch creation - "after 9pm,before 6am" in timezone
Europe/Zurich, Automerge - At any time (no schedule defined).

🚦 **Automerge**: Enabled.

♻ **Rebasing**: Whenever PR is behind base branch, or you tick the
rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update
again.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR was generated by [Mend Renovate](https://mend.io/renovate/).
View the [repository job
log](https://developer.mend.io/github/dotnet/dotnet-operator-sdk).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0MS4xMzAuMSIsInVwZGF0ZWRJblZlciI6IjQxLjEzMC4xIiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6WyJkZXBlbmRlbmNpZXMiXX0=-->

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

test/Directory.Build.props

@@ -12,7 +12,7 @@
         <PackageReference Include="FluentAssertions" Version="8.7.0" />
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
         <PackageReference Include="xunit" Version="2.9.3" />
-        <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4">
+        <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
             <PrivateAssets>all</PrivateAssets>
         </PackageReference>