fix(admin): Note drop of MariaDB 10.3 support

Signed-off-by: Ferdinand Thiessen <[email protected]>

Author: susnux

admin_manual/release_notes/upgrade_to_30.rst

@@ -8,7 +8,7 @@ System requirements
 * PHP 8.1 is now deprecated but still supported.
 * PHP 8.0 is no longer supported.
 * PostgreSQL 9.4 is no longer supported.
-* MariaDB 10.5 is no longer supported.
+* MariaDB 10.3 and 10.5 are no longer supported.
 
 Web server configuration
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