chore(deps): Upgrade NuGet package dependencies

[idubnori]

Summary

• Upgrade test, assertion, and Selenium dependencies to their latest stable releases.
• Upgrade NUnit3TestAdapter from 5.2.0 to 6.2.0.
• Keep Selenium Support and WebDriver aligned at 4.46.0.
• Retry a failed CI test task up to two times to handle transient Google search responses.

Why

Keeps the sample current with supported package releases and the latest NUnit test adapter.

Validation

• Local build and tests were intentionally not run at the author's request.
• Azure Pipelines builds and runs the full parallel test suite on Ubuntu, with up to two retries for a transient test-task failure.