Add official support for MariaDB using the MySQL dialect

[mikeminutillo]

In https://github.com/Particular/NServiceBus.Persistence.Sql/issues/339 we tested the SQL Persistence against MariaDB 10.5.8 with the MySQL dialect. All tests passed.

In order to fully support this to our list of supported SQL implementations, we'd want to add it to the list of database engines that we test against as part of our continuous integration process.