README note that MariaDB 10.3 and Ruby 2.6 are supported

Author: sodabrew

README.md

@@ -523,14 +523,14 @@ As for field values themselves, I'm workin on it - but expect that soon.
 
 This gem is tested with the following Ruby versions on Linux and Mac OS X:
 
- * Ruby MRI 2.0.0, 2.1.x, 2.2.x, 2.3.x, 2.4.x, 2.5.x
+ * Ruby MRI 2.0.0, 2.1.x, 2.2.x, 2.3.x, 2.4.x, 2.5.x, 2.6.x
  * Rubinius 2.x and 3.x do work but may fail under some workloads
 
 This gem is tested with the following MySQL and MariaDB versions:
 
  * MySQL 5.5, 5.6, 5.7, 8.0
  * MySQL Connector/C 6.0 and 6.1 (primarily on Windows)
- * MariaDB 5.5, 10.0, 10.1, 10.2
+ * MariaDB 5.5, 10.0, 10.1, 10.2, 10.3
 
 ### Ruby on Rails / Active Record