Log Message:
games/ruby-squib: update to 0.18.0

pkgsrc change: drop ruby26 support.

0.18.0 / (2021-10-26)

Features:

* Placeholders! Missing images to svg and png can be replaced by a
  placeholder (#339)
* New config option: img_missing. When an image is missing, warn or error to
  the console (#339)
* save_sheet learned how to rotate individual images! (#301)

Compatibility:

* Because of the features above, the new default behavior is to warn instead
  of errors on a missing file
* Ruby 2.7 is officially our minimum Ruby, since Ruby 2.6 will EOL in about
  six months from now