devel/ruby-rgl: update to 0.6.0

0.6.0 (2023-02-22)

What's Changed

* feat: implement bidirectional adjacency graph #78. New class
  BidirectionalAdjacencyGraph which implements the protocol defined in
  module BidirectionalGraph.

* Bump actions/configure-pages from 2 to 3 by @dependabot in #74

* Fix: codeclimate badge by @monora in #77

* fix(doc): #79 class comments in generated doc by @monora in #80

(taca)