Hello! The package libmariadbclient-dev was a real binary package in Debian Stretch and has been an empty transitional package already since the Buster release. So you can safely change libmariadbclient-dev -> libmariadb-dev in both Buster and Bullseye.
See https://packages.debian.org/search?keywords=libmariadbclient-dev&searchon=names&suite=all§ion=all
