[ANN] wxRuby3 v1.6.1 released

[Martin Corino]

This is a minor update to align wxRuby3 with the latest wxWidgets 3.3.1 release.

What's Changed

• target wxWidgets 3.3.1 release by default
• add support for latest wxWidgets persistence classes
• updates for latest VScrolled (template) class changes
• add missing Array<Integer> support for Wx::Variant
• add extensive PropertyGrid testing
• minor bugfixes and improvements
• remove Ruby 2.5 support, make Ruby 2.7 minimally required version
• update wxWidgets master branch compatibility to at least commit 49c6810948f40c457e3d0848b9111627b5b61de5

For more details see the original release announcement here: https://github.com/mcorino/wxRuby3/discussions/417