Change functional tests library

[askpt]

Description

The SpecFlow library was deprecated on December 31st, 2024. We should transition to another library currently actively supported for our functional tests suite. We are currently blocked from upgrading xUnit since SpecFlow depends on xUnit version 2.
One of the possibilities is Reqnroll.

More information

• https://specflow.org/
• https://github.com/reqnroll/Reqnroll
• chore(deps): update dependency xunit.runner.visualstudio to v3 #331