deps: update vstest monorepo to v17.8.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
Microsoft.NET.Test.Sdk	17.7.2 -> 17.8.0
Microsoft.TestPlatform.ObjectModel	17.7.2 -> 17.8.0

---

Release Notes

microsoft/vstest (Microsoft.NET.Test.Sdk)

### [`v17.8.0`](https://togithub.com/microsoft/vstest/releases/tag/v17.8.0) #### What's Changed **Full Changelog**: https://github.com/microsoft/vstest/compare/v17.7.2...v17.8.0

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

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

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by Mend Renovate. View repository job log here.