MariaDB connector/node.js 2.1.5

minor evolutions:

Full Changelog

• CONJS-115 Batch improvement
  • supporting array of parameters if only one parameter per query, not only array of array
  • supporting empty array for query without parameters
• correction on licence tag: LGPL-2.1-or-later (was tag LGPL-2.1+ that is deprecated)
• dependencies update