Log Message:
lang/ruby26-base: update to 2.6.3

Update ruby26{,-base} to 2.6.3.  Here is release announce:

Ruby 2.6.3 Released
Posted by naruse on 17 Apr 2019

Ruby 2.6.3 has been released.

This release adds support for New Japanese Era “令和” (Reiwa). It updates
the Unicode version to 12.1 beta (#15195), and updates date library (#15742).

This release also includes some bug fixes. See details commit logs.