Support DBD::MariaDB

[tyrrminal]

Since version 5 (Oct 2023), DBD::mysql cannot be installed without MySQL 8.x. This ranges from inconvenient to unacceptable for applications using MariaDB (particularly considering that the the necessary mariadb libs are packaged with the official perl docker images, while mysql's are not). Fortunately, since the release of DBIx::Class::Storage::DBI::MariaDB in August 2023, DBD::MariaDB is a viable option for most applications as a drop-in replacement for DBD::mysql.

Unfortunately, Sqitch is hardcoded to use the DBD::mysql driver for MariaDB databases, which requires the installation of DBD::mysql 5.x (and consequently MySQL 8.x), or the no-longer-maintained/6-year-old DBD::mysql 4.x. Would you consider adding support for DBD::MariaDB as a much cleaner solution?

[theory]

Sqitch relies on URI-db for DBI params. Perhaps we should change it to prefer DBD::MariaDB in URI::mariadb?

That said, Sqitch built and tested with DBD::mysql on all supported versions of MySQL and MariaDB as recently as three weeks ago. It doesn't use MySQL, but does use mysql-client and the line that installs DBD::MySQL seems to work fine. I guess that's because it builds against the MySQL libraries and not MariaDB?