Replace InMemoryDatabase in tests

[A-Guldborg]

Found issue while developing #264

See https://stackoverflow.com/questions/74907256/ef-7-new-executedelete-and-executeupdate-methods-not-working-on-an-in-memory-d

Due to sqlite3's in memory database not being compatible with new bulk sql operations, we cannot test any of the .NET 7.0 bulk update/delete methods ExecuteUpdate and ExecuteDelete.