Windows CI build failing `SqlListenerTests.RecordsSql` for .NET Core 3.1

[mattjohnsonpint]

The CI build for Windows started failing recently for SqlListenerTests.RecordsSql, only on .NET Core 3.1.

https://github.com/getsentry/sentry-dotnet/actions/runs/4202147697

Looks like database spans have disappeared.

[mattjohnsonpint]

This is due to Microsoft.Data.SqlClient 5.1.0 (which we bring in transitively through LocalDB) dropping support for .NET Core 3.1. They still have .NET Standard support, but SqlDiagnosticListener is not implemented for that target.

We can workaround for our tests by pinning the last working version.

Note that this means end-user applications that are still running on .NET Core 3.1 or .NET 5 should not update to the latest Microsoft.Data.SqlClient. If they do, they will no longer see DB Spans in Sentry.