* Lossless image optimization (using ImageOptim).
This shouldn't change the visual appearance of any images. ImageOptim
was run with the highest compression setting except that JPEG metadata
stripping was disabled because some users prefer to avoid stripping
JPEG metadata.
* Update READMEs that have Changelogs for themes impacted by lossless image optmization change.
* Update duotone presets and apply to image and cover blocks.
* Remove duotone from block specific attributes.
* Title the variations.
* Remove title from default theme.json.
* Replace screenshot.
* Fix php version.