------------------
* Use ``utf8mb4`` character set for encoding strings. This seemed to be broken
for emoji on older versions of MariaDB (10.1 or 10.2?), so ``utf8`` was
previously used, however this may have only been a display/``COLUMN_JSON``
issue on such older versions. MariaDB internally now defaults to ``utf8mb44``
for dynamic column strings. Since this changes the output of serialization
slightly, please test before upgrading. Also you probably want to use
``utf8mb4`` for everything else MariaDB in your application if you aren't
already - it is the default on MySQL 8+.